BACK TO HOME
I started out to simply try to find the most accurate load for my rifle. At the time, all of the published information said to just keep trying different powder charges, bullets and primers. Although I looked in many reloading manuals, and read ever periodical I could find, I was unable to learn of any methodical way to adjust loads to produce accuracy. I did however find a tremendous amount of non-sense, circular logic, and flowery words without meaning. As the result, I started to research the topic on the Internet. Eventually, between some very old periodical articles, and some very new Internet postings, I was able to assemble a fact based logical approach to economic load development of accurate (small group) ammunition.
As the information began to accumulate, I found myself interested in publishing my findings so that the next hand loader could find and benefit from my research.
Of course, many other topics came up, and questions were asked. So I decided to compile what I know and what I believe to be true into an indexed web page.
What follows is the result.I have found that a short concise list of safety rules is much easier to teach, learn, and use.
If you are teaching someone to shoot, you may load the gun for them, put the gun on safe and hand it to them. This should be done so that the student has a full and complete view and explanation of how the gun is loaded, and what additional steps are necessary to make the gun ready to fire. This activity should be conducted on the range, and the instructor is responsible for ensuring safe range operation.
If you are in a situation where you must use a gun for self defense, or where you must provide a gun to someone for self defense immediately, it would not be unreasonable to pass a loaded firearm from one to another. The firearm safety should be engaged prior to passing the weapon. This is an inherently risky operation, and should be anticipated in training.
Crossing a fence. If you hand your gun to another person during a maneuver, for example; crossing a fence, the gun should be unloaded, cleared and then handed to the other party. The gun(s) should stay unloaded until everyone has passed the obstacle. In point of fact, hunting guns should stay unloaded until the hunt has progressed to the point where the action of loading might cause game to learn of your presence.
Casually handing a firearm to another. This is a major source of accidents! Always unload before transferring. Always check for yourself when receiving.
1. Trigger Disconnector. If the slide is out of battery (pushed back even a fraction of an inch) it is unsafe for the pistol to fire, and the disconnector will disengage the trigger.
2. Grip Safety. There is a panel in the back strap (part of the handle) that is depressed when you grasp the gun with the firing hand. This panel is held open by a spring and until it is depressed the firing mechanism is locked. In other words if the gun is not in a hand it won't go off.
3. Hammer Half-Cock. If the hammer were to fall from any position above a half-cock, without the trigger being pulled, the hammer will catch in a very deep notch and prevent it from hitting the firing pin. Thus a fall on a hard surface, or a snag on the hammer will not allow the gun to fire.
4. Firing Pin Safety. The firing pin is not long enough that it can contact the hammer and the primer at the same time. There is a spring keeping the firing pin away from the primer. When the hammer hits the firing pin it imparts enough inertia to move the firing pin across the gap and hit with enough force to ignite the primer. This is to prevent a fall on a hard surface from firing the gun. Also some (Colt Series 80) 1911's have a firing pin block that prevents the movement of the firing pin unless the trigger is pulled.
5. Thumb Safety. This switch locks the slide forward, prevents the trigger from being pulled, and locks the hammer at full cock. It was originally requested by the US Calvary to provide a mounted soldier the means to make a loaded gun safe to re-holster. By locking the slide forward re-holstering could not force the slide out of battery and prevent the gun from firing the next time it was needed.
6. Trigger Guard. This is the frame extension that surrounds the trigger and is present on nearly every firearm. Its intention is to prevent foreign objects from activating the trigger. You must put your trigger finger inside the trigger guard to pull the trigger.
Modern striker fired pistols based on principles similar to the GLOCK series have these features:
2. Trigger disconnector (same as 1911 above).
On some modern pistols there is a 'magazine disconnector' which is designed to prevent the gun from firing if the magazine is removed. The theory is that as a last resort you could eject the magazine before the weapon leaves your control. Perhaps moderately useful during storage to prevent children from activating unsecured guns, while permitting quick action by only inserting a magazine. In most cases a magazine disconnector is a death trap waiting to be sprung on the shooter who has one round in the chamber and is the midst of reloading. That round CAN NOT BE FIRED until the magazine is fully inserted, and MIGHT be fired inadvertently if the trigger is being pulled while the magazine is inserted. Firearms having magazine disconnectors require additional extensive training to avoid all the problems they create.
3. Loaded chamber indicator. This is usually the extractor which is designed so that when a case is present in the chamber it rests proud of the surface. It is always tactile, and sometimes visual.
4. Manual safety. On some striker fired pistols the manufacturer has included a manual safety that typically operates similar to the 1911. When not present, and a DA/SA trigger is in use, the decocker may be present. It's purpose is to relax the main spring by lowering the hammer against a stop that prevents the hammer from reaching the firing pin.
5. Trigger Guard.
Some semi-automatic pistols rely on a heavy and/or long trigger pull to prevent accidental discharge. These are sometimes referred to as DA/SA (Double Action / Single Action) triggers.
DA pistols (as opposed to revolvers) featuring a long heavy first shot trigger pull, followed by much lighter subsequent trigger pulls are not my favorites. The second shot followup is always going off before the sight picture is correct (because the trigger is so much lighter than it was a split second ago), and typically these pistols require a 'decocking' mechanism, to return to a safe (and long heavy trigger pull). I find the decocker to be one of the most 'evil' inventions, right up there with magazine disconnectors! It is just plain wrong to allow a hammer to fall when not either firing, or dry firing. I can not make myself 'believe' in the safety of the mechanism, and I don't like the abrupt stop the hammer experiences because this is the road to fatigued metal. In any case, if you own one of the pistols with this feature (Walther PPK, S&W, etc.) please train yourself and remember all the rules of firearms safety apply at all times, so NEVER EVER operate a decocker with the muzzle pointed in an unsafe direction. Always get your finger off the trigger and out of the trigger guard before decocking any of these style pistols.
Modern revolver safeties generally consist of the following: Bars that must be moved into position between the hammer and the firing pin by action of the trigger to allow transfer of the hammer energy to the firing pin. Firing pins that do not have the mass to detonate a primer no matter how hard the revolver may fall, and various mechanisms to ensure the alignment of the chamber with the barrel at the moment of firing. They are strong guns with substantial frames made from high strength materials and can withstand much higher operating pressure than older revolvers.
Antique revolvers safeties generally consist of making sure you don't carry a live round in the chamber that is under the hammer. This is accomplished by loading one round, skipping one round, and loading 4 more rounds in sequence, then cocking and lowering the hammer on the empty chamber. Its a skill you should develop early in your training on an antique revolver like the Colt SSA. Failure to abide by the rule to keep an empty chamber will (not may) cause the gun to fire when the hammer is struck. Immediately unload or reload the revolver and make sure the hammer rests on an empty chamber after firing. Simply easing the hammer down, or using the half cock notch will result in undesirable conditions.
Revolvers come in two types, single action, where the hammer is cocked manually for each shot, and double action, where the trigger can be used to cock and fire the revolver in one continuous motion. Modern double action revolvers invariably possess single action capability in addition.
As you can see, a lot of thought has gone into making guns safe. A safe gun is one that will not discharge inadvertently, but will fire instantly when the operator so chooses. The trigger is the final safety. To defeat the final safety only requires some amount of pull and the gun will fire if it can. If you put your finger into the trigger guard, you have provided a means for external forces (think the side of your holster, or an opponent) to mimic pulling the trigger. Keeping your finger (and everything else) out of the trigger guard area eliminates the threat that the gun can fire due to negligent handling. In particular keep your finger off the trigger AFTER you have ceased firing and MOST ESPECIALLY, keep your finger off the trigger when re-holstering your gun. Train yourself by performing slow draw, aim, fire and re-holster drills. With an unloaded gun, watch what happens if your trigger finger stays in the trigger guard. Some holster designs will cause you to press the trigger. Know your equipment. Always train the way you want to fight.
Do not shoot at things you can not positively identify. A very large percentage of accidental shootings happen because the shooter does not take time to positively identify the target before firing. Know you are shooting at the correct target, and conversely know that if you bullet penetrates your target it will not damage anything around or beyond the target. For example if you are hunting and a shot at a great trophy appears on the crest of a hill, you should wait until the animal moves off the crest of the hill, so that a hit or a miss will land where you know the background. Shooting over hills, and across bodies of water, and along or across roads have been responsible for many firearms accidents. There is one time, and only one time when you shouldn't spend too much time worrying about the background, or where your bullet may go, and that is when you are forced to fire on another human. In that one case, most courts have held that any damage resulting from a justified shooting is the fault of the perpetrator rather than the victim. This is the result of the notion that all the results of a bad deed are the fault of the one committing the bad deed. You should of course be aware of your immediate surroundings, and if possible move to ensure you do not shoot into say an adjacent bedroom where you know someone to be sleeping, but in the event your are forced to fire, then fire for effect. The good news is that in your home you can plan ahead to know where safe shooting lanes are located, and you can plan ahead to use equipment and ammunition that is suited for your circumstances.
Return to top
Marksmanship is the art and science of firing a hand held or shoulder fired gun.
Competition marksmen live in a world of rules. Their shooting position(s) are dictated by the rules for the discipline or the match. NRA Smallbore and High Power marksmen have prone, sitting, kneeling and standing positions to master at the same time they skill with their hardware. Tactical marksmen must master shooting from sometimes difficult positions while being able to utilize a wide range of support options. Hunters pretty much have no rules about positions, but will find that prone, sitting and standing as well as using whatever support is available are the options.
Beginners would do well to master the conventional match positions of prone, sitting, and standing first. Then master shooting from a shooting bench, and perhaps last make an effort to use kneeling until you are comfortable and accurate in that position.
Natural Point of Aim - When you have completed getting into position to shoot, close your eyes, relax all of your muscles. Count to 5. Open your eyes and check to see where the rifle is pointed. If it is not pointed directly at the place where you want the bullet to strike, adjust your position and repeat. Whey you have found your natural point of aim, you should be able to remain in that position for an extended period of time and you should not have to 'muscle' the gun to get onto or stay on the target.
Prone is considered to be the most stable position. I have found that shooting from a bench is much more stable, repeatable, comfortable, and produces much higher accuracy for most people. Bench technique is a lot more than just sit down and bang away. Lets cover some of the basics for each position:
Prone will get you out of the line of incoming fire as much as possible, allow you to sneak up on targets, and crawl around below the top of the brush etc.
Prone With Sling - In this position the shooter lays flat on their stomach, pelvis and ankles. Elbows and shoulder support the rifle. A sling connected to the front of the rifle's stock and wrapped around the 'support side' (opposite of the trigger finger) forearm and upper arm, may or may not be connected to the butt of the rifle. Properly adjusted the sling will allow the support side hand's grip to control elevation with little effort as it slides back and forth along the forend. Shooters body should align just slightly to the support side as viewed from above. The sling should be tight, and the butt of the rifle should be tight against the shoulder. Follow through the shot by riding the recoil with the rifle.
Prone with Support - In this position the shooter will be more directly in line with the rifle, and the support side arm will not be involved in supporting the rifle, as it is supported by something (bipod, backpack, etc.). The support hand can either help control the vertical by supporting the butt, or help stabilize the rifle by ensuring it doesn't fall off the support. The support hand should be available to make sight corrections (dial up the scope), or adjust parallax (on a modern long range scope). The support side hand should not in any way support the gun forward of the butt. Follow through the shot by ensuring the rifle recoils straight back into your shoulder. You may support the butt of the rifle with a bag or a mono-pod.
Sitting will get your line of sight above the grass (most of the time), allows you a little bit of lateral (tracking) movement, may offer a position you can remain in for long periods comfortably.
Sitting With Sling - Cross your legs at the ankles, or place your feet slightly apart. This position changes quite a lot based on foot position choice. In competition crossing ankles, and leaning far forward so your elbows are outside your knees is typical, and makes this position even more stable for me than prone. The open sitting position is much more suitable for hunting or tactical applications where movement is necessary. In the 'closed' position the rifle sling is employed the same way as in prone, and the rifle is held tightly to the shoulder. Follow through by ridding the rifle's recoil. In the 'open' version of this position, the elbows are placed to force the knees apart. If you have a spare rope or belt, to constrain the movement of your knees this can be a long term comfortable position. In the open version of sitting follow through is again a tight sling and riding the rifle's recoil.
Sitting With Support - This position can become difficult if you loose flexibility in your core (eg get fat), because in order for it to work well, you need to lean into the rifle and you don't have the luxury of the rifle's weight, or a sling to help with that movement. Essentially you will be in a 'kip' position, and muscle strain (bad for shooting accurately) will start immediately. Generally sitting with sling is more stable, unless terrain offers support for the shooter. There is also a 'high sitting with support' (long bipod, tripod, shooting sticks etc.) position that may include a short chair, or kneeling with both knees on the ground, while your weight rests on your heels. Follow though in these supported positions may be best if you utilize 'free recoil' - in other words, your body does not resist the recoil, and does not support the rifle. When the rifle recoils, it does so free of obstruction (for a few inches). It does not take much distance between the butt pad and the shoulder to create a free-recoil setup, however in that distance the rifle is free to accelerate and with heavy recoiling calibers that may be enough to cause problems. In free recoil you firing hand should be setup in such a way that it does not influence recoil. Many shooters put their thumb on the back of the trigger guard, and their trigger finger on the trigger, and have no other contact with the rifle. You should work up to free-recoil, its a good way to get a scope cut, drop your rifle, dislocate your shoulder, etc. Be sure you know what's going to happen. Heavy (12-13 lb) low recoil rifles (308 Winchester and below) generally have a low enough recoil impulse that free-recoil is practical and you can learn it with little risk. Don't start off with a 6 lb 7mm Magnum!
Kneeling raises your line of sight above what you had in most sitting positions. It also allows for rapidly assuming the position, and rapidly resuming stalking, or tactical movement with a minimum of noise and visual signature. The accuracy potential from kneeling is probably twice to three times better than from standing unsupported (offhand).
Kneeling With Sling - Once again a tight sling can increase your stability significantly in this position. Your support side foot should be flat on the ground, your shin straight up, your knee bent. The support side elbow should be just over the knee. The trigger finger side elbow can be down, but if you shoot a heavy recoiling rifle, putting that elbow parallel to the ground will open your shoulder pocket and allow absorbing much more recoil. Follow through in kneeling with a sling, as before, to have tight sling, and ride the rile throughout the recoil pulse.
Kneeling With Support - Generally this position only happens if you have to work from under some obstruction. Typically any shot you would take from this position can just as easily be taken from standing with support, and with about the same accuracy.
Standing, also known as 'offhand' is the most challenging position to shoot accurately from. In this position a sling is generally a detriment to accuracy. Since most hunting and tactical rifles will have a sling attached part of your training for this position will be to secure the sling so that it does not impart movement.
Standing Unsupported - In this position you will not be able to hold your sight picture for any more than a few seconds. There are at least two ways to address this problem with technique. First what I call the 'shotgun approach' which works well for quick shots on larger targets. Mount the rifle so that the sights are in the correct position instantly. Your eyes should be looking at and focused on the target as you mount the rifle. The moment the rifle is mounted, you should be able to pickup the sights. If you try to stand still you will wobble around in circles (we'll talk about that next). To keep from wobbling around you will need to muscle your gun in such a way that the sight track across the aiming point (AP). If you move too quickly this won't work as well as if you move slowly and deliberately. The amount of movement is very small, maybe not more than 2-3 MOA (Minutes Of Angle). As you push your sights across the AP coordinate your trigger finger to break the shot just before your sights reach perfect alignment. This movement is very similar to the way a shotgun is fired. It takes practice to achieve high accuracy, but once you get the hang of it, you can take on difficult targets at high speed, with a great deal of success. The reason it works, has to do with how your muscles don't want to hold still as much as they want to move. You can apply a very smooth movement across the target, but you can't hold very still on target.
Standing Supported - In this position you will be erect behind shooting sticks, tripod, or rested against a support (tree, door frame etc.). Your rifle will be constrained at the point where the support occurs. If you choose to put the support near the balance point of the rifle, it will be easy for you to move up and down. If you put the support nearer the muzzle, you will have to make gross movements to change your point of aim, and those movements will by necessity be made by your entire body, or by repositioning the support. This position will feel very un-natural until you have practiced it a lot. It will also take quite a while for you to determine the correct length for adjustable legs, and position (fore and aft) on the rifle. One trick to really 'clean up' this position is to back into a tree or other stable support. You won't believe how much your upper body wants to move around until you constrain that movement. In standing supported you may find the sights are wandering all over the place just like standing unsupported, but if you watch closely, you'll see that they tend to oscillate in a typically circular pattern. By watching the pattern, you can predict when the sights will approach the AP. If you have excellent trigger control, you would take up 3/4 of the trigger weight as soon as your sights are close to the AP. Hold that. When your sights come around on their oscillation, take some of the remainder as the sights approach the AP, and hold as the sights depart. Continue this until you have what Col. Jeff Cooper called a 'surprise break'. This trigger technique is valid for all positions, at all times, but you will get the best training opportunity in Standing Supported.
A word about follow through; The ideal situation is for you to have zero reaction with the shot breaks. Be like a bag of sand, just absorb the recoil, hold the trigger, and DO NOT BLINK. That last one is perhaps the single hardest thing to do for most people. You will have to convince your subconscious first to delay the blink, then since 'nothing ever happens' to do away with the blink completely. Blinking is a reaction to an unexpected event typically recoil, or sound, or for scoped rifles, the loss of sight picture. Blinking will prevent you from seeing where your shot impacted, which will prevent you from making a correction if necessary. One technique I've used to overcome blinking is to become so engrossed in watching the scene unfold after a shot, pickup the trace, see the 'glint' from the bullet, watch for impact, etc. that I actually don't blink. It takes a while (unless you shoot tracers - that's a real shortcut!) until you can stall the blink response long enough to see anything of interest, then all of a sudden you will 'get over it' and be able to watch everything. Once you have that mastered, you can work on getting recoil to push your rifle straight back, and returning the rifle to 'battery' all during bullet flight time. If you want to work up in stages, I recommend you start by learning to hold your trigger all the way through the shot.
Return to top
You will hear instructors mention 'The Fundamentals Of Marksmanship' very often. Mastery of the fundamentals is key to shooting accurately. So what are these fundamentals?
According to the US Army these are four fundamentals of Marksmanship:
- Steady Position
- Breath Control
- Trigger Squeeze
This is a link to the US Army Study Guide
The Washington State Criminal Justice Training Commission Patrol Rifle Course added the following:
- Sight Alignment
- Sight Picture
- Trigger Manipulation
- Follow Through
This is a link to the document
Another US Army guide is much more simple:
- Properly point the rifle at the target
- Fire the rifle without moving it
This is a link to the web page, there are some very good graphics on this one.
Do not allow the barrel to come into contact with anything.
Front rest should be close to the front end of the stock, leaving sufficient room for recoil.
Rear rest should be close to the rear of the stock. Observe that the rear rest allows for 2-3 inches of rifle movement during recoil.
Position yourself behind the rifle so that your head on the stock is close to the same position as if you were standing. Often this can be accomplished by changing your seating height. One of the reasons I recommend a Drummer's Throne type of stool for bench shooting.
Position your right hand to lightly grasp the rifle and reach the trigger with the middle of the pad on the tip of your index finger.
Position your left hand to either operate the forward rest controls (elevation and windage), and/or squeeze and steer the rear bag. If your hand is near the rear bag when you shoot, make sure it is out of the area where the stock can hit it during recoil.
You should seat the rifle into your shoulder with no gap. If you leave a gap with a high recoiling rifle it will cause more discomfort. Do not pull the rifle hard into your shoulder, unless you can pull it the exact same way repeatedly. Try not to change the recoil dynamics.
Use tripod shooting sticks to support the front of your rifle for positions from prone to standing. There are short tripods for prone and taller much more adjustable tripods for everything else.
Use bipod shooting sticks when weight is an issue.
Use a stock mounted bipod when shooting from prone to sitting. Learn to pre-load the bipod so that the rifle will recoil naturally.
Use a backpack if nothing else is available.
Use a rear mounted monpod to support the rear of the rifle when possible.
This is the most stable position. For practical applications, this position is best used with a rest at both the forend and the toe of the stock. These rests may be tripod, bipod, or monopod devices, or bags designed for this purpose, or a field expedient rest composed of pack, jacket, rocks, logs, etc.
The forward rest should be located as far forward as is practical to reduce motion as much as possible.
The rear rest should be located under the toe (bottom) of the stock as far to the rear as is practical. The rear rest should be able to be adjusted by the shooters weak side hand to control elevation.
The rifle should be supported so that in recoil it moves directly to the rear.
The shooter should be positioned straight behind the rifle to absorb the recoil in a straight line. This promotes rapid return to the natural point of aim, which should also allow rapid re-engagement of the target.
For traditional match shooting where no rests are allowed, the shooter should use a sling (strap) to apply tension between the weak side upper arm and the sling swivel at the front of the stock. The sling shold wrap around the shooters arm, and have just the length to allow a tight position. In this position, the shooter should be aligned at an angle to the rifle so the weak side can support the rifle sling and create a triangular structure for support.
Learn to use a sling to steady the rifle. As mentioned above, a sling is not desirable for a fully supported prone position, however it does become useful for practical sitting, kneeling and squatting positions. Practical rile shooters should make a habit of constructing solid shooting positions with and without the use of a sling. For practical and hunting positions, creative use of the sling will add safety and support to the rifle system
Learn to avoid transmitting your brachial pulse to the sling.
In traditional match shooting shooters had to contend with their pulse being transmitted to the rifle system by way of the sling. The primary culprit is the brachial artery in the upper arm. The pulse effect can be mitigated by placing the sling above or below the center of the arm, and by padding at the source of motion.
Use a sling for stability.
Learn to shoot both cross legged and open legged.
Cross legged, place elbows over your knees, hook yourself into the position
Open legged place elbows into the 'pockets' of your knees and push out. For practical shooting, you can use a belt or rope to hold your knees together to significantly stabilize open legged sitting.
Use a sling for stability. Learn to place your weak side elbow over your week side knee.
A sling will only slightly improve stability in this position, and requires a significant time to adjust correctly. Learn to shoot 'free hand'. In standing there will be a lot of movement. Learn to control the oscillations so that your sights come onto the target predictably. Learn to squeeze as the sights approach alignment, then hold your squeeze until the sights begin to approach again. Successful shots from standing are often done quickly and dynamically (like shotgun shooting). Practice with low cost equipment and ammunition. Dry fire as much as you can.
Most of us are born with an innate desire to use one eye or the other to 'see' things. Assuming you start out as a youngster with equal eyes, you probably will develop a dominance in the eye on the same side as your 'handedness' eg; right handed and right eye dominant. If one eye is stronger it may become the dominant eye even though it is on the opposite side eg; right handed and left eye dominant. It is possible (and desirable) to at least be able to switch eyes with the hand that's doing the work. In the shooting world, this would manifest as being comfortable switching the eye you sight with when you switch the hand holding the firearm. Where rifles are concerned, it is extremely desirable to achieve the ability to be ambidextrous with both your hands and your eyes because of the way the rifle stock naturally places the sighting plane in line with the eye on the side where the rifle is being shouldered. There are any number of practical reasons to train yourself, and those you train, to be able to shoot proficiently from either shoulder. The same is true for handguns, however because there generally is no stock to shoulder fixed relationship it is possible to simply move the gun into line with the dominant eye.
There are several techniques that work. The following is one quick and simple way to show a shooter his or her dominant eye:
Place your hands together at full
extension with your index fingers and thumbs forming an opening.
Make the opening as small as practical, say 2-3 times larger than the target, and use your hands to block out as much of the rest as possible.
Look through the opening at a distant (10 foot or so) target. It is important that the target be at least 10 feet to get this right.
While keeping your concentration on the target, and your hands in the same position, slowly bring the opening toward your face.
As the opening gets closer to your face it will tend to center up on the eye you are using. This indicates the dominant eye because no effort was made to choose an eye in the beginning.
Once you understand that the image you see is the composite of the images generated in both eyes (binocular vision), you will begin to understand how to mentally select the eye you desire to use.
Another drill that my father was taught in the Army in the 1920's uses just your index finger (either hand) held up like a front sight at arms length. Again the target must be at least 10 feet (or more) distant for this to work.
Look at the target. Focus on the target. Hold the tip of your finger just under the target (don't look at your finger, keep looking at the target). While you are looking at and focusing on the target, you should see two fingers, and both should be out of focus and appear semi-transparent. Each eye sees the finger from a different perspective, your brain puts the image of the target together in a single plane, and your finger(s) are in the foreground out of focus.
Here comes the fun part. While continuing to focus on the target pick one of the finger images and place it under the target. If you chose the left image, you are right eye dominant, if you chose the right image you are left eye dominant. Without changing anything else, close your right eye. Did the finger continue to be under the target? If it did, you are using your left eye, and the right image of your finger. If you open both eyes, then close the left eye you should see your finger jump out from under the target. If you happened to do it the opposite way, just reverse everything I just said.
The very useful part of the finger drill is that you can very quickly learn to move your 'chosen' eye from side to side, and you will learn what it feels like to choose an eye, and rapidly you will develop the ability to use either eye as your dominant eye.
If you are training someone in the finger technique, you use your (pick one) eye as their target, and run them through the close eye, switch eye, then to graduate with both eyes open consciously pick which eye to use. As the target, you will see the student's finger tip move back and forth between their eyes as they run the drill. If the student's finger gets stuck on their nose, try making the distance a little greater, or go back to explaining what a sight picture looks like.
If you have never tried an eye dominance drill like this one, I recommend you do so right this minute. Did you feel it 'pull' on your eye when you swapped dominance? That is like doing your first push up. Keep at it and you will be able to do it with ease.
When I get a few more minutes I'll try to sketch up this drill so you can see better what I am talking about, or just contact me if you have any questions.
As firearms technology progressed, it became apparent that a system was necessary to help the shooter point the gun at the target. Shotguns were found to work well with small bright beads, while rifles and pistols being that they fired single bullets, needed something more precise.
There are a number of variations on the front and rear sights that have been found useful over the years. Their purpose is always to align the barrel so that the bullet impacts where desired. Bullets do not travel in straight lines, and so sights for precise and long range work differ considerably from sights for short range fast work.
In this document, I am only going to cover rifles, and long range, so we will keep the discussion of sights confined to those useful for that purpose.
Open sights consist of a post or bead front sight, and a rear sight with some sort of notch to view the front sight through. The front sight must be centered side to side between the ears of the rear sight. A post front sight should be chosen to nearly fill the gap in the rear sight. The top of the front sight must be level with the ears of the rear sight. The sights should be zeroed so that the shot will hit just above the center of the front sight at your maximum point-blank-range.
The peep sight is designed to act as a very precise rear sight. In looking through the small hole in the center of the rear sight you will observe a vignette (shadow circle) with a clear center. The peep sight can increase depth of field much the same way that a camera aperture works. The center area is very small, thus ensuring a close alignment of the front and rear sight. The front sight may be any one of several designs; blade, post, circle, bead. Adjust the sights so that the shot hit the center of circles, or top middle of blades, posts, and beads.
Holographic sights project an aiming point so that it appears to be floating in the air before your eye. Because there is only one aiming point, and it follows the line of the barrel, it often appears to move more quickly than expected, and can wander all over the display area. Sights with a large display area make it easier to pickup the aiming point. A good way to develop speed with a holographic sight is to pretend the rifle is a shotgun and bring it to your shoulder while both watching the target, and paying attention to where the barrel points.
The ocular end of the scope is the end nearest to your eye, and the objective end is nearest to your target.
Ocular focus (focus the aiming point): The first step in adjusting a telescopic sight to your eyes is to adjust the ocular focus. Point the scope at a neutral (white) surface. Closer is better. You do not want to be able to look at the surface you point to, you only want to be able to see the reticle (aiming point). If the aiming point is out of focus, move the ocular focus to bring the aiming point into focus. Close your eyes for 10-20 seconds, then when you open them quickly determine if the aiming point is in focus. Make an adjustment to the focus. Repeat the quick recognition drill. Your eyes will bring the aiming point into focus if you continue looking too long. When you think you have the focus correct, wait a few minutes and do the quick recognition drill again. Continue adjusting focus until the aiming point is in sharp focus immediately, and stays that way.
Objective focus (remove parallax). Tactical and varmint telescopic sights have an objective focus. Typical hunting scopes have their parallax set to something like 100 or 200 yards and fixed there. The primary purpose of the objective focus is to remove parallax. You can determine if parallax is present by looking at a target through the scope while moving your head (and eye) slightly side to side, or up and down. If the aiming point appears to move on the target then you are observing parallax. If the aiming point remains stationary on the target then parallax has been removed (and the scope is focused at that distance). Tactical scope use a knob on the left side of the scope while varmint scopes allow you to screw the objective lens in and out to achieve focus. Both have a scale, usually in yards, to help preset focus. Typically even on high end tactical scopes the parallax adjustment numbers are incorrect. Always conduct a parallax check and adjustment before firing.
For quick action drills, and hunting or combat situations where time is of the essence, you can ignore parallax settings if you are confident your eye is in exact alignment with the centerline of the telescope. As you move your head in/out behind the scope, you will at some point begin to see a dark ring around the image. When the dark ring is the same size all around the image, your eye is centered, and although parallax is not removed, the cross hairs will be in the correct position relative to the target. This technique is most useful on fixed parallax hunting scopes.
Typical hunting scopes have ocular focus, elevation and windage adjustments. The elevation and windage typically are protected under a cap, and use a coin for turning leverage. US made hunting scopes typically have ¼ MOA adjustments, and may have a 'click' for each increment. Often the increments are quite different, and the adjustment rate is not very precise. Once adjusted to place a shot at the aiming point the scope is said to be zeroed. The distance at which this occurs is the scope zero range. Typical hunting scopes are zeroed at the beginning of the hunt, and shots taken at ranges beyond the point-blank-range, or to correct for wind are compensated by aiming away from the desired point of impact. In other words, the shooter may hold over the target so the bullet will impact the desired location. Hold over is very subjective and only allows for a little additional ethical range. You can use ballistics programs to suggest an optimal zeroing range for a given target size (ethical kill zone size). By adjusting the scope to place the bullet exactly in the center of the target at this range, you achieve the benefit of maximizing the allowable over and under impact so that you can aim directly at the desired point of impact for shots up to the maximum point blank range. Some shooters 'zero' their hunting scope to impact high at a closer range (typically 100 yards) by a certain amount (typically 1-1/2 inches). This technique has value, but is wildly inaccurate unless based on elevation obtained from ballistics programs which are given accurate information about all of the conditions involved.
Target scopes of a certain age were a tube with no elevation or windage controls built in, rather the scope mounts contained the machinery to point the scope, and adjust accurately in the desired range. In this setup, the scope often was allowed to slide front-to-back during recoil to protect the delicate silk thread, or natural spider webs that were used for cross hairs. Ocular and objective focus were the same as varmint scopes. Modern target scopes are often fixed power versions of tactical scopes. Tactical scopes have progressed to the point they are accurate enough for nearly all target work.
The modern tactical scope is able to resolve very small targets at very long ranges, has a wide zoom capability of 3, 4 or 5 times (ie 3-9 is 3 times, 3-12 is 4 times, 6-30 is 5 times), has very precise and repeatable adjustments that can be heard, felt and returned to the rifles zero point under adverse conditions. Nearly all tactical scopes have reticles that have an aiming point plus additional features to allow for accurate hold off and ranging. The modern tactical scope should feature reticle and knob calibration in the same angular measurement method, either MOA (Minutes of Angle), or MILS (Milliradians).
Mil-Dots: Mil stands for milli or 1/1000. In the case of scopes that's 1/1000 of a radian. A radian is an angular measurement system having π (Pi) radians per circle. There are 0.2908 MILS per MOA, or 1 MIL = 3.438 MOA. See MOA below
Mil-Dots come in several flavors, the US Marine Mil-Dot is a football shape, the US Army Mil-Dot is a circle. Mil-Dots are found almost exclusively in tactical scopes. Some tactical scopes use Mil-Dot reticles and MOA turrets, a situation that increases complexity for the shooter and spotter exponentially. Mil-Dot scopes with Mil turrets and FFP reticles are intuitive, but, for a shooter familiar with MOA, it takes time to become used to the larger MIL increments. The advantage is that turrets and reticles are provided in 1/10 Mil increments which while about 10% larger than ¼ MOA increments, and are easier to work with than fractions.
MOA stands for Minute Of Angle. In a circle of 360 degrees, each degree is composed of 60 minutes, each minute composed of 60 seconds. Most scopes sold in the US market have claimed MOA calibration, however many deliver IPHY (Inch Per Hundred Yard) divisions. 1 MOA = 1.0472" at 100 yards. 1 IPHY = 1.000" at 100 yards. Most US ballistic data is provided in MOA. The combination of MOA reticle and MOA turret in an FFP scope is very intuitive. Unfortunately MOA turrets and reticles are calibrated in fractions of an MOA, either ½ or ¼ MOA, increasing difficulty calculating adjustments. Some target scopes and peep sight have adjustments as small as 1/8 MOA.
FFP: A reticle placed in the first focal plane changes size proportional to the scope magnification so that any stadia on the reticle are useful at all power settings.
SFP: A reticle placed at the second focal plane remains constant size throughout the scopes magnification range. Any stadia (marks) on the reticle are accurate only at one power setting. The vast majority of hunting and inexpensive scopes in the US market are MOA and SFP type scopes.
Whether bench or position shooting, the expansion and contraction of your chest during breathing will move your point of aim significantly. The way to correct this is simply to stop breathing as soon as you acquire a sight picture, and complete the shot before you resume breathing. While it sounds easy, and it can become so second nature that you are not conscious of performing it, controlling your breathing does take some practice to perfect.
Generally accepted teaching is to inhale normally, exhale 1/3, and stop. Refine your sight picture, perform your trigger squeeze, and follow through. If you take too long, and that time is determined by how much oxygen your body is consuming at the moment, you will begin to become agitated and anxious, followed by tremors and loss of visual acuity. You can not make an accurate shot under those conditions, so before you start trembling you should hold your squeeze, maintain your sight picture, exhale, inhale, exhale, inhale and exhale 1/3, and pick up where you left off. You should not take particularly deep breaths, nor should you try to over oxygenate as this will cause you to be unstable for a period while you burn off the excess oxygen. With practice target acquisition, sight picture, breath control, and trigger control will become so deeply ingrained in your mind and body that you will be able to perform the entire sequence with no effort what so ever.
When shooting with a sling for support, particularly in prone, you may notice your front sight (or scope reticle) bouncing up and down in time to your pulse.
The brachial artery runs down the inside of your upper arm.
Your sling has come in contact with this artery, and your heartbeat is moving the rifle.
Placing a pad on the inside of your arm, or moving the sling up may eliminate the problem.
If you shoot enough, and you practice enough, you will discover that shooting accurately is more of a mental problem than it is a physical problem. About that time you may notice that you can control your heartbeat. It's a 'zen' sort of thing, and all I can tell you about how to do it, is to shoot about 1,000 rounds a week for several years while attempting to score X's on the old international smallbore target (the X is a speck in the center of a 0.22" circle fired at 50 feet), your shot must be within 0.11" of center to touch the X.
More realistically, a hunter may experience sever heartbeat interference due to exertion prior to the shot. A good way to mitigate the problem is to learn the 'free recoil' method of holding your rifle, wherein you have as little contact with the rifle as possible. It is always ethical to use any and all stability enhancing techniques as possible when hunting or in combat.
Triggers come in several types. The triggers that are most useful for accurate long range shooting are of a type that has little to no 'take up', that 'break' "like breaking glass", at pull weights around 3 pounds, and have very little over travel.
Target triggers that have these characteristics and break at ounces are only useful on the target range.
The advantage gained by the lighter weight trigger over the 3 pound trigger is minimal, and if you shoot much you will develop what I call an educated trigger finger.
The educated finger is confident in taking up the slack (2/3 of the trigger's pull weight) immediately. It is capable of holding any amount of tension on the trigger for several minutes (through many breathing cycles), and it is an expert at lying to you just enough that you don't quite know exactly when you have pulled enough to make the trigger go off.
The educated trigger finger takes its commands directly from the educated eye.
The brain only has executive control over the eye/finger team.
As the eye sees the sight picture approaching perfection, it tells the finger to increase tension.
The finger increases tension slowly until the eye tells the finger that the sight picture is deteriorating, at which point the finger holds what it's got, until the cycle repeats.
The brain can over-ride this coordinated effort to either abort the shot, or more likely it will anxiously interfere and make the finger mis-behave by jerking the trigger, which spoils the shot, which causes the brain great anguish.
When the brain does not interfere, the eye/finger team cause the gun to fire when the sights are correctly aligned, and an accurate shot results.
But because the brain wasn't really involved, there is no joy.
Paradoxically if joy and anguish get involved your shooting will suffer because your brain isn't very good at shooting. The more you get excited by a good shot, the less likely you are to be able to make a good shot.
The brain will play every trick in the book to get involved in the act of shooting.
One of the most difficult actions to perform is to ignore a shot, but that ultimately is what follow through is all about.
Another way to look at it, is that your brain really doesn't have a clue what time is, so it organizes things in a cause/effect sequence for you to experience. You brain lives in total darkness, it gets vision from sensors called eyes, tactile sensation from receptors all over your body (particularly sensitive places like your trigger finger), and sound from sensors called ears. While you are attempting to concentrate on breath control, sight picture, and trigger squeeze your brain is also worrying about things like "Is this shot going to hit the target?", "What is the recoil going to feel like?", "Am I going to get hurt by the recoil?", "Am I going to get hurt by the sound?" and about a million other things all at the same time.
The more you allow your brain to be involved in the act of shooting the more likely you are to make a bad shot.
One of the classic bad shot situations occurs when your brain makes your trigger finger jerk the trigger.
Another classic problem is when your brain tells your eyes to close to protect them from the 'Big Event' that's about to happen (gun goes off). You can't hit what you are aiming at with your eyes closed! So we need to keep the brain as far removed from the act of shooting as possible.
When I was learning to shoot, my coach told me that I could blink all I wanted AFTER the bullet hits the target. I spent several months telling my brain that it could blink AFTER the gun goes off, and now I just tell my brain that I don't need to blink AFTER the gun goes off, because NOTHING EVER HAPPENED that I needed to blink for.
Bottom line is that to shoot accurately and with precision the shooter must divorce his brain (emotions and self-preservation) from shooting. The eye/finger team must be trained and then allowed to function without interference, and the rest of the body is to act as a great large sand bag - no reaction - until well after the shooting stops.
Do not mess up the shot!
Don't jerk the trigger.
Apply smooth steady increasing pressure against the trigger.
Don't anticipate the shot.
It is natural to want to 'control the trigger', and make it go off when your eye says it should. This is the essence of 'eye-hand' coordination. It is also the source of one of the greatest violations of the fundamentals of shooting. It is inevitable; if you anticipate the shot, you will 'jerk' the trigger, disturb your aim, and miss the target.
To avoid anticipating the shot, squeeze the trigger with a slow steadily increasing pressure on the trigger. Force yourself to do this correctly by dry-firing (practice shooting without ammunition), until you think you have it. Then go to see how you are doing, practice with live ammo. The moment you detect trigger jerking, dry fire until you stop anticipating the trigger.
Dry fire a lot. But, and this is huge. Dry fire perfectly.
Perfect practice creates the sequence that you will use when you do a task naturally without thinking out each step. To achieve perfection in position, sight alignment, and trigger control, practice dry firing so that each shot is done slowly and perfectly until you start to pick up speed. When you notice yourself messing up a shot, start over slowly and build back up to a natural rhythm.
Never practice bad habits. Correct them immediately so that your practice time is not wasted, and has the most benefit.
Don't muscle the gun.
To find your natural point of aim, (the position in whch your body naturally points the sights at the target).
Assume your shooting position with the rifle in firing position.
Close your eyes and settle into your cheek weld, grip, stance, etc.
Open your eyes and without moving the rifle, determine where you are pointing your sights. Correct your body position (stance) until you can repeat the sequence and the sights remain on target.
When done correctly, you should be able to maintain this position for hours at a time.
Call the shot.
Shooters use an O'Clock method to locate 'things' as a direction from a known reference point, and then either inches, MOA, or MILS to indicate the distance from the known reference point.
My wife has no end of problems with this, so I'm going to assume someone reading this is also having problems …
First – agree on the known reference point.
For 'formal' targets that's the Point Of Aim (POA), the center of the target, with 12 O'Clock straigh up.
For conditions affecting the bullet or the shooter, the shooter is the center of the clock, with 12 O'Clock straight ahead.
For 'informal' targets, game and bad guys, the known reference point becomes some natural feature that is easily identified and communicated between shooters, and spotters. Again with 12 O'Clock straight up.
Second – Superimpose a clock face on the known reference point, with 12 O'Clock straight up.
Third – Describe the direction to the thing of interest (bullet hole, new target, etc.) as the hour hand of the clock pointing toward the item of interest. Thus if something is above and to the left of the known reference point, it would be at 10:00 or 11:00 O'Clock. When you get more proficient it could be at 10:30.
Fourth – Describe the distance to the the thing of interest.
You can estimate distance at the target if you have a good feel for it. Could be in inches, feet, yards, meters, etc. Use the measurement unit that makes the most sense. This method is the least precise in most cases.
You can measure (or estimate) the distance as a function of the angle between the known reference point and the thing of interest. If your scope or binoculars have a grid for measuring angles, use that. The more you get used to using MOA or MILS to measure and correct your sights on a paper target, the better you will get at estimating distances in terms of degrees, or minutes / mils. The advantage here is that the shooter presumably has a reticle with the same measurement system, and can precisely locate the thing of interest.
One quick angular measurement is 'finger widths' – hold your hand at full extension and count the number of fingers between the point of reference and the object of interest – hold your hand so that the direction from the point of reference to the object of interest is at right angles to your fingers. After fingers run out, use the number of hand widths, etc.
Assess the shot.
At the moment the shot goes off, you should be surprised and therefore you won't blink until well after the shot happens. Keep the image of the sight picture in mind at that instant. Where were your sights pointed?
Use the method described under 'calling the shot' to record where your sights were pointed, and where the shot hit. As your skill progresses, you will be more likely to accurately determine where your sights were pointed, and will find your shot impacting at or near that point.
If there was a problem with the shot, you jerked it, the wind changed, the target moved, etc. record that too.
Correct the sights or aiming point as necessary.
As you become proficient in calling your shot, and find your shots landing where you called them, you can use this information to make sight corrections or accurately than simply adjusting from the POA.
Log the shot.
Keep a record of every shot.
Refer to previous shots in similar conditions to establish a starting point for each new shot or group of shots. Your log book should contain the information listed under DOPE below.
Return to top
DOPE is what shooters have been calling their 'Data On Previous Engagements' since the early 1900's. It is a formalized method of recording critical information about each shot, with the goal of eventually providing sufficient information that the shooter can achieve first round hits on targets at extreme ranges under extreme conditions. Shooters keep a DOPE book for each rifle. Within the book there are sections for recording the data about the rifle, about the ammunition, about the target(s), and about each shot fired.
By categorizing, compartmentalizing, standardizing an recording information about each shot we take, we can build a reference work from with it is possible to gather, keep and use information we would otherwise loose. This information is valuable in allowing us to make corrections based on previous similar engagements and to allow us to modify our corrections based on changing conditions. We also gain a better memory of things like the number of shots fired through a barrel, and the effect various physical parameters have on our shooting. The DOPE book also contains charts and other reference material we may use to arrive at a firing solution.
NOTE: Even though there are many very good and accurate exterior ballistics programs available and even embedded into some of our environmental measuring equipment, keeping a DOPE book will have benefits as your memory of events, settings, conditions fades with time. The DOPE book is a journal designed to record both the technical data and the shooters observations.
The most useful location data includes Latitude and Longitude because as you learn to shoot longer distances the direction of fire over the earth, as well as the location on the earth become important to the calculation of the firing solution.
At the very least use a location you can find and refer back to with LAT/LON when you get to that point.
Time of year indictes a general set of parameters in case you don't have the ability to measure them directly.
Establishes chonological order.
Above or below Sea Level in feet or meters.
ASL (Above Sea Level).
AGL (Above Ground Level), 'Angels'.
Station pressure (the absolute pressure where you are) is the number you need. You can get this number from the sea level pressure and your altitude and temperature, or simply get this number from a local barometer (Kestrel, iPhone app, etc.)
Generally in the US this value is in inches of mercury (in/hg).
The dry bulb (shade) temperature at your location.
In the US in degrees Farenheit. (ºF)
The percentage of water in the air. (%RH)
As the temperature goes up, the air becomes thinner (density goes down).
To use the formula above, you need to convert your temperature from Fahrenheit to Kelvin
The formula to make this conversion is:
For your DOPE it is sufficient to record pressure,
temperature and humidity.
Including altitude will permit referencing the results to standard atmosphere at sea level should you ever desire to do so at a later date using the formulas above.
Each of these conditions affects how you see objects and perceive dimensions, distances, size, shape and movement.
Hazy – Haze or smoke (stuff between you and your target)
Overcast – Some clouds. Estimated % cloud cover.
Changing – Clouds periodically blocking sun, casting racing shadows.
Dawn or Dusk – Sun near horizon, very low angle light, often light hitting bottom of clouds, very long shadows.
The ability to 'read' the wind, and to 'estimate the wind' are vital to successful long range shooting because for a typical long range cartridge, after the bullet has traveled about 500 yards, the displacement of the bullet by the wind is far greater than the combined error of the shooter and the ammunition. A successful long range shooter must be able to integrate the wind over the course all the way to the target and provide a 'wind call' consisting of the wind speed and direction (always reported as the direction from which the wind blows) to an accuracy of about one mile per hour.
Anemometers are tools that are calibrated to display the speed of the wind, and optionally act as a weather vane to indicate the direction of the wind.
To achieve accurate readings, the typical shooters anemometer must be aligned so that the full force of the wind acts upon the detector. Aligning the detector so that it is parallel to the path of the bullet will not produce the correct wind speed because the detector (usually a propeller) does not react proportionally to the prevailing wind, but rather tends to record the maximum wind from a wide angle of presentation.
The anemometer only informs of the local wind. Shooter observation of the wind downrange will determine if this reading can be used reliably.
First, it is important to know that the wind that affects the bullet initially (wind at the firing point) is often going to have the largest impact on the location of the bullet downrange. This is because once the bullet has been deflected, there is no force, except another wind, that can move the bullet back toward it's unaltered course.
Second, it is important to note that winds downrange can and will affect the path of the bullet, sometimes adding to the deflection, other times subtracting from the deflection the bullet experiences at the firing point. These wind effects can be added together as a 'vector summation' to arrive at a total deflection. When doing so, however it is necessary to include the increased time the bullet spends in each say 100 yards of range, due to velocity reduction induced by drag. More time in a given wind will result in larger deflection.
In locations with totally open flat surface between shooter and target the wind is likely to be fairly similar across the entire distance. If grass is long enough to react to the wind, you may see 'bands' of wind 'rippling' across the grass. This effect is due to the way the wind is blowing in rolling circular bands and can help you figure out the percentage of the effect across the course.
Initially this effect moves straight up in calm air and appears as vertical wavy lines, quite pronounced when viewed through magnification. As the effect continues, and the day progresses, wind will occur as cooler, denser upper air is drawn to replace the lighter warmer air near the surface. This wind will cause the vertical wavy lines to tilt.
The bottom of the wavy line will stay put where the heat caused the air to expand, and the top of the wavy line will move in the direction of the wind. When viewed through magnification (spotting scope or telescopic sights) the direction is nearly impossible to determine because of the two dimensional nature of the image.
The strength of the wind can be measured quite accurately for low speed wind, by the angle of the mirage.
15° tilt is caused by 1-3 mph wind
30º tilt is caused by 4-7 mph wind
90º tilt is caused by 8-10 mph wind
Mirage can be measured at increments downrange by focusing the spotting scope (or tactical rifle scope) at ¼, ½, ¾ of the distance to the target and observing the mirage effect.
For the streamers used in High Power competition:
15º = 3-3/4 mph
30º = 7-1/2 mph
45º = 11-1/4 mph
60º = 15 mph
75º = 18-3/4 mph
Flags or streamers can be used to
measure the wind by noting the angle between the flag's long edge and
Generally, dividing that angle by 4 will yield the wind speed in MPH.
Golfers have developed interesting
wind flags. See Wind Gear Direct.
For streamers made from surveyors tape that are 3 feet long these values apply:
It is best to do your own research on the relationship between wind speed and your local flora, as there is a very wide range of behavior.
5-8 mph Tree leaves in motion
12-15 mph Small trees sway
15-20 mph Larger trees sway.
0-3 mph Barely felt on the face
3-5 mph Lightly felt on the face
When you begin to shoot beyond 500 yards the motion of the Earth has a meaurable affect on the behavior of your bullet. By the time you are shooting 1,000 yards, the effect can be measured in inches on the target.
Its not exactly true, but an easy way to visualize the Coreolis effect on bullets is to imagine firing a bullet due East at a distant target, then turn around and fire a bullet a an equally distant target due West. The true explination is much harder to remember and apply, and the difference is minor.
The Earth surface turns toward the East – to get the sun to come up on that side).
The bullet takes time (a lot of it) to travel from the rifle to the distant target. The time is the same for both targets.
During the time the bullet is in flight to the East the Earth has turned enough to raise the target several inches, and the target to the West has been lowered the same amount.
Firing to the North and South causes targets to move to the East by several inches, so a shot to the North will hit to the left and shot to the South will hit to the right.
Firing at any angle will cause a combination of the effects (up/down & left/right).
The effect is most pronounced at the equator where the surface of the Earth is moving fastest.
Modern ballistics calculators want to know your firing
location in LAT/LON format plus your direction of fire in degrees TRUE
NORTH to enable calculating the effect and producing a correction to
the firing solution.
NOTE: What's wrong with this expinaton is that the bullet motion contained the Earth's rotation at the moment it left the barrel, and its frame of reference is that of a spinning globe. It does not leave that frame of reference just because it's in the air during flight. However as with centripiedal force, when the constraint has been removed, eg the bullet exits the barrel, it would (if no drag were encountered) travel in a straight line, the sum of all the forces applied at that momement, and not a curved line that would contain the rotation vector. For the full story read the WikiPedia article 'Eotvos Effect'.
Firearm - record the following information for future
Return to top
For the sake of completeness, and thus understanding, here is the sequence of events that result in a bullet going from a loaded round into ballistic flight (exiting the muzzle) in excruciatingly minute detail.
The example load is 308 WINCHESTER / 42.8 VARGET / 175 SMK / HDY MATCH CASE / CCI LARGE RIFLE PRIMER / 0.044" JUMP.
This load is safe in my rifle. Please refer to my general disclaimer before duplicating this load.
QuickLoad was used to calculate the interior ballistics data below.
QuickLoad has been calibrated to case length, case volume and COAL. Burning rate (Ba) has been adjusted to agree with measured muzzle velocity. Velocity was measured with a MagnetoSpeed chronograph.
This load has at 98.8% fill ratio.
Processes, operations, and characteristics in this region are referred to as interior ballistics, and are completely under the control of the loader/shooter, and the rifle.
Bullet reaches the rifling.
Case neck reaches the end of the chamber.
Case shoulder (at datum) contacts the chamber (at datum)
Case body, or bullet encounter obstruction.
When the case stops moving forward the extractor is forced over the rim of the case while the ejector plunger is loaded against the base of the case, thus forcing the case to 'reference' off the inside edge of the extractor and the back of the groove in the case rim. This tends to leave a gap between the bolt face and the case head.
These conditions continue as the bolt is cammed shut.
If the case is stopped before the bolt is fully shut by the case shoulder contacting the chamber shoulder, the case may straighten up and be forced into full contact with the bolt face. It may happen that the case is not touching the chamber walls except at the datum point, and alignment of the case and thus the bullet is determined by the squareness of the bolt face and case head.
If the case is stopped by the bullet reaching the rifling the
camming action of the bolt may be sufficient to force the bullet to
begin engraving the rifling. In this case, it is possible to have the
bullet stick in the barrel if the case is removed before firing. In
which case a large amount of unburned powder may put the rifle out of
action until cleaned.
If the case is stopped by jamming the neck of the case into the chamber at or beyond the point where the chamber is relieved to accept the neck, the force fo closing the bolt may swage the case neck into the bullet, or simply not allow the case neck to expand away from the bullet during firing. In either case, extreme pressure will be experienced, and it is likely to damage or destroy the firearm. Keeping case necks trimmed to a length shorter than chamber minimum is critical to safety.
In the event a push feed action is chambering a fully sized round with the bullet seated to a depth so as to not touch the rifling, then the case is being pressed hard to the right side of the action, and whatever clearance was available is all located on the left side (due to the ejector pressing on the case head). The base of the case is not touching the bolt face and thus not contributing to concentricity. The case neck is off center in the chamber just as the body is. In this condition it is impossible to achieve concentricity, and this is the reason why accuracy improves with neck only sizing.
Extractor. The case head is engaged with a mechanism designed to pull the case from the chamber after firing. If the extractor is holding the case tightly to the bolt face the firing pin may detonate the primer before the case can move forward. This is not a desirable condition.Shoulder contact with the chamber. Absent any other retardation, the case will move forward in the chamber to the point where the cone that makes up the inside of the chamber between the body and the neck will stop the case on the cone that makes up the transition from body to neck. There is a reference dimension located at half the diameter of the shoulder called the datum line, or simply datum. The measurement is from case head to datum. This is where 'shoulder bump' is measured by reloaders. Case stopping on the datum line is the desired condition. Note that at this point there is a gap between the bolt face and the case head. Typically 0.002” is the desired gap.
Blast wave from primer detonation forces bullet out of case neck and either into contact or into engraving by rifling.
See “Primer Output and Initial Projectile Motion
NOTE: Aberdeen Research Lab concluded that the engraving forces (rifled barrel vs smoothbore) are essentially nil in affecting the rate of bullet movement, and gas pressure generation. The notion of loading to jam length causing a pressure spike is incorrect.
NOTE: This may also be happening: My best guess has to do with the subtle variations in pressure vs time during the time between shot start and (for example), when the rifling is engraved. During this period the available volume is increasing as is the pressure. By increasing the charge weight, the initial volume decreases as does the available volume at the point of engraving. Powder burning characteristics (Ba or Burning Rate in particular) change as a function of pressure, thus at some point in the charge weight variation tested, the burning rate changes inversely to the charge weight enough to produce similar pressures for a several tenths grain charge change.
The major diameter of the bullet enters the leade, a smooth straight section of the barrel just toward the muzzle from the case neck and before the rifling that is a few ten-thousandths of an inch larger than the bullets major diameter. The leade guides the bullet toward the forcing cone; a chamfer between the leade and the origin of the rifling. The leade supports and guides the bullet into engagement with the rifling. Accuracy is significantly affected by how concentric the bullet is to the forcing cone at this moment in time because the center of rotation of the bullet must be as close to the center of mass of the bullet as possible. Variations in case neck thickness, bullet jacket thickness, and accuracy of machining of this area are critical to launching a bullet that is spiraling without wobble.
The major diameter of the bullet enters the forcing cone. At this point the rifling begins to 'engrave' or 'upset' the bullet. The bullet must begin to rotate due to the spiral of the rifling. The gas that has been escaping around the bullet is now sealed into the chamber by the bullet to barrel deformation. The relationship between the centerline of the bullet, center of rotation of the bullet, and the centerline of the barrel have now been set. Ideally these center-lines should be identical.
Depending on how the bullet was seated in the case to begin with, it may have to travel some distance, probably less than 0.080" or as little as 0.000" for 'accuracy' handloads to be loaded single shot, and perhaps well over 0.100" for rounds loaded to feed in magazines in long lead rifles similar to the Weatherby design.
With the 308 WINCHESTER / 42.8 VARGET / 175 SMK example used elsewhere here, and according to QuickLoad calculations, when the bullet has traveled 0.040" to engage the rifling, or the bullet's 'jump' is 0.040"; 0.050 Seconds have elapsed, the pressure behind the bullet is about 35 psi, and the bullet is moving toward the muzzle at about 10 fps. The thing to remember is that the bullet enters the rifling quite slowly and gently.
NOTE: This graph was published by Aberdeen Research Lab in 2016 showing the position vs time for M855 (55 grain 5.56 NATO) and M856 (55 grain 5.56 NATO Tracer) bullets during the first 450 nano seconds after firing. Note that the bullet passes through contact with the rifling and engraving with no discernible variation in the rate of position change or measured force.
NOTE: A mili second: 0.001 Sec is 1/1,000
(1 thousandth) of a
A micro second: 0.000001 Sec is 1/1,000,000 (1 millionth) of a second.
NOTE: This graph was published by Aberdeen Research Lab in 2016 showing the acceleration and velocity of a 5.56 NATO M855 bullet during the first 400 nano seconds after firing. Primer induced velocity reaches to about 0.17 mS where acceleration from propellant burning begins to takes over.
NOTE: At 0.0004 seconds the M855 projectile has traveled 0.75" down the bore, it is traveling (in that instant) 156.25 fps.
NOTE: Read the complete report by Aberdeen Research Lab: Primer Output and Initial Projectile Motion.
NOTE: The transition zone between primer induced velocity and powder induced velocity is likely the area affected by varying the seating depth of the bullet.
In our search for the ideal load we are looking for consistent muzzle velocity and consistent group size. Once a case, primer, bullet, powder charge has been decided upon the only parameter available to change is the bullet seating depth. Varying the seating depth changes the available initial volume, which no doubt changes the point on this chart where bullet velocity and the resulting increase in available volume, are governed by gas generation.
The case is pushed into contact with the bolt face.
If the primer was partially blown out of the primer pocket, it is reseated by the bolt face as the case head moves to the rear. This motion may be as small as 0.002" (neck sized case due to 'spring back') or as large as the maximum variation in SAAMI headspace, which in the 308 Winchester is 0.010"
NOTE: When you set your resizing die you are controlling the relationship between the case and the chamber. You must be careful to ensure that the CBTD (Case Base To Datum) dimension is within the SAAMI Headspace dimensions.
Pressure increases as the bullet moves forward. The volume available to the expanding gas increases. Gas generation increases very rapidly.
At some point in time, the pressure inside the case becomes sufficient to expand the case body toward the confining chamber walls. As pressure increases stiction occurs. (stiction is 'static friction').
Under some conditions stiction will occur before the case head is in contact with the bolt face. When this happens the case stretches and over time may separate forward of the web area.
Ideally the case will first contact the bolt face, then expand no more than 0.002" in length to bring the case shoulder into contact with chamber. Brand new and full length resized cases will typically expand more. Resizing only the case neck between reloading (for the same chamber) will limit the stretching of cases.
Various styles of extractors may hold the base of the case closer in contact with the bolt face during primer strike, leaving room at the shoulder for case expansion.
NOTE: One major goal of accurate ammunition manufacturing is to ensure the bullet is concentric to the center of the bore at the moment of firing.
As the case shoulder is bumped further toward the case head, the cartridge looses a bearing surface upon which to elevate the bullet into line with the bore.
Extractors generally are on the side of the bolt, and do not exert much upward influence on the cartridge case, so as support at the front is removed, the case tends to lay in the bottom of the chamber. Do not assume the case neck can support the case as the chamber is several thousandths larger in diameter in that area to allow bullet release.
Seating the bullet to a zero jump length or longer will force the case into better alignment, but may also cause the bullet to stick in the bore if the case is extracted prior to firing.
The ideal situation is to have the cartridge case shoulder in tight or not more than 0.002" loose contact with the chamber while the case head is flush on the bolt face prior to firing.
The bullet travels 1.3" toward the muzzle, volume for gas expansion increases, the volume of gas produced increases and peak pressure of 58,166 psi observed.
The bullet has accelerated to 891 fps. 0.361 seconds have elapsed.
The bullet travels 6.1" toward the muzzle, gas pressure has decreased to 29,100 psi, approximately 1/2 of maximum.
The bullet has accelerated to 1,907 fps. 0.633 seconds have elapsed.
The bullet travels 26" and is at the muzzle. The pressure is 6,450 psi, velocity is 2695 fps, and 99.92% of the powder has been burned.
NOTE: The air in the barrel at the instant of firing is compressed by the escaping gas and the accelerating bullet and creates an initial gas jet that has some potential to disturb the point the barrel is aimed to, however the more important effect this gas jet can be used for is to penetrate and remove any muzzle cover (electricians tape) that may be applied to a hunting rifle to keep foreign debris out of the muzzle. The escaping air will easily remove the muzzle cover with no effect on the shot.
The now unconstrained gas creates a jet effect as it exits the muzzle unrestricted. The jet creates a significant portion of the recoil energy produced. Typically the rifle has barely moved along its recoil axis at the point in time where it no longer has any contact with the bullet. The gas accelerates as the pressure equalizes inside and outside the barrel and then disperses in the air beyond the muzzle. High speed video shows the gas cloud typically overtaking the bullet out to a distance of one to two feet, before it dissipates, and the bullet emerges from the gas cloud.
The very rapid expansion of the gas causes the gas to cool dramatically. The 'BANG' you hear is actually more about the gas cooling off quickly than anything else.
If the muzzle is not square to the line of the bore, then gas may be released early on one side of the muzzle, this force can cause a bullet to yaw in an effect that is not altogether dissimilar to the 'PIT' maneuver used by Highway Patrol to cause a suspect vehicle to swerve.
If there are any obstructions in the bore near the muzzle that occlude the bore (stick into the area occupied by the bullet) then bullet deformation may occur, and if the obstruction is quite close to the muzzle may cause a shift in the point of impact. Lead and copper fouling creates this type of obstruction in the portion of the barrel where bullet velocity is maximum.
If there is any deformation of the bore near the muzzle that does not occlude the bore, the chances are very good that accuracy will not be affected, unless said deformation causes gas to be released unevenly to such an extent that yaw is induced in the bullet.
From this point onward the bullet is no longer under the influence of the shooter or the rifle. Characteristics in this region are referred to as Exterior Ballistics. For a thorough treatment of the behavior of bullets in this region please refer to the collected works of Brian Litz.
The Celestron C90 MAK telescope with the appropriate erector and eyepieces can resolve bullet holes to just about the maximum distance the current mirage conditions will allow - generally 30 cal to about 300 yds. This spotting scope is quite inexpensive compared to the typical shooting spotting scope, and is quite a bit more fragile.
You can color your bullets with a permanent colored marker, and some of that color will rub off on the target paper as the bullet travels through it. For cases where the bullets impact a little apart from each other, this technique (which might take a little time to perfect), is the fastest, easiest, and least expensive way to get the 'which bullet made which hole' information.Some people have suggested that a ladder test should be a group fired with each charge increment. If you do this, you'll need to fire enough shots to burn your barrel out before you are done, and unless each shot in the group has nearly the same muzzle velocity you'll need to fire enough at each charge increment to get a valid statistical sample to determine where the center of the group is (not the group size). Each shot in the ladder test tells its own story quite accurately. There are a number of actions you can take to improve your group size once you figure out your powder charge
Right about here, a lot of you may be wondering about Scott Satterlee's 10 shot Load Development Ladder Test. Scott noticed that there is a velocity change plateau in the typical incremental charge ladder test, and that the lowest velocity variation load occurs in the middle of this plateau.
I have not been able to find any theory, finite element analysis, or simulation that explains why this plateau occurs, but occur it does, and it can be used to quickly choose a correct powder charge for an accurate long range load.
There are a number of videos, and much internet discussion of how to
perform Scott's test. Here's a link to the 6.5 Guys interview with Scott Satterlee on
the subject. One observation that Scott makes and I agree with is
that once a velocity has been identified for a given rifle, case,
primer, bullet, the powder can be changed, and as long as the powder
charge achieves the same velocity, it will be an accurate load. I
believe this is a demonstration of all of the barrel movement
observations detailed above. Due to the variations in burning
rate and total energy of each powder, I believe there are a limited
number of powers that will demonstrate suitability over the entire
range of use. For example, a faster powder may, when the correct
velocity is found, only fill the case to 75%, and because it has such a
large open space within the case, it may not ignite the same way every
time, and thus have an unusably large velocity spread. Ancient
wisdom tells us that the best loads occur at above 90% fill ratio, with
the slowest powder that will achieve the desired velocity.
Ammunition must fit the chamber for best accuracy.
Simply 'being in the chamber' is not fitting into the chamber. To
fit, a loaded round must be very close to all of the dimensions of the
chamber, so that the center line of the bullet is positioned as close
as possible to, and parallel with the center line of the barrel. The
bullet must travel down the barrel with its center of rotation very
close to its center of mass.
When a virgin or full length resized case is chambered, there is
typically a significant amount of slop in the length and diameter of
the case. Case misalignment in the chamber can destroy any
benefit of bullet to case concentricity.
When a new case is fired it expands under tremendous pressure to fit
very tightly into the chamber machined into the barrel. As the
temperature of the case returns to normal, the case (because it's
brass) contracts very slightly in diameter and length. The fired case
is now as close to the chamber's dimensions as it can be. Try not to
mess that up! Correct neck sizing alone is sufficient to reload this
piece of brass, and if it is done with a conventional die, ensure (by
measuring before and after) that the neck expander does not alter the
headspace, or diminish concentricity. Hand dies are the best because
they don't ever pull the case from the neck, and they are small,
accurate, concentric, fully support the case, and easy to use anywhere.
CASE BASE TO CASE DATUM (CBTD)
To know when the case should be trimmed.
Generally assumed to be about 0.002" smaller than the chamber neck diameter.
Measured from shoulder datum line to case head. Generally taken to be between 0.001 and 0.002 inches less than bolt face to chamber datum line due to brass spring back after firing. As you are resizing your brass (conventional full length resizing), keep referring to this measurement to ensure you do not change it more than -0.002" (also known as "bumping the shoulder back"). The difference between this length and the bolt face to chamber datum line is properly the rifle's headspace, or 'space for the head to expand into during firing'.
Make up a solution of 1 shot of water and just a tiny speck
of dish soap. The soap is to reduce surface tension so that you can
accurately install the water into the fired case.
Use a pipette (long skinny dropper) to fill a fired case and check that no bubbles exist in the case. Stop filling when the water is exactly at the top of the case neck.
This test should be conducted on a fired case that has been trimmed to your standard trim length.
Weigh 10 empty cases and keep track of case number and weight.
Fill a case to exactly full with the water solution.
Weigh the filled case. Deduct the dry weight. This is the weight of the water representing the interior volume of the case. The exterior dimensions of the case have been constrained by the firing chamber. Thus the variation in water weight between cases represents the variation in interior volume, which is caused by manufacturing processes which typically leave one side of the case thicker than the other.
Record the average of 10 or more cases for each headstamp (and or lot #) of brass you use.
If the case volume (by weight of water) goes down, there is a good chance that if the load is near Pmax in the original brass, the new brass will be over Pmax, perhaps significantly.
This situation occurs routinely when you move from using say a Hornady case to a Prime or Lapua case. Prime and Lapua have thicker walls, less interior volume, and will create higher pressue with the same load.
You should start over at the beginning, to work up a new load, when changing to cases that vary in case volume by more than 1% of the 10 case average established originally. (for 308 size cases, 223/5.56 cases are more sensitive).
Do not let this dimension get to within 0.001" of the FIRED NECK DIAMETER or you may experience a pressure event.
The cases you use for testing should have been fire-formed to the chamber, trimmed to length and deburred at a minimum, and only neck sized. This will give you reasonable uniformity in presenting the bullet to the rifling and providing uniform case volume.
There are many procedures you can apply to your brass to increase uniformity, however they only add a very small increase over the fire-form, neck size protocol. Arguably the next most important case preparation you can do is to make the neck wall thickness uniform, thereby centering the bullet on the barrel axis more uniformly. Neck tension uniformity is important, and making the neck wall thickness uniform tends to make neck tension uniform. Interestingly bullet speed in the first few thousandths of an inch of its initial travel are quite slow. In my 308 Winchester example, the 175 SMK is moving at 62 fps by the time it has moved the first 0.010", about the same speed as though the bullet had fallen 1.4 feet. Obviously the force required to upset the bullet into the rifling is going to come from pressure not velocity! Also obviously, the bullet has plenty of time to 'rattle around' if it isn't presented perfectly. Making your ammunition co-linear with minimum runout is probably the second most important thing. The first of course is to select a powder and charge that can tolerate variations larger than your error in producing it.
Brass cases will eventually work harden wherever the dimensions are changed during the firing-reloading cycle. In particular the case neck is likely to become so brittle that it cracks. Annealing the case neck is fairly easy to do with nothing more than a propane torch, a deep well socket, a drill to spin the socket, and a semi-dark room to allow you to observe the case color change with the application of heat. Oh yeah, you'll need somewhere to put your hot cases until they cool, and somewhere to put your hot tools to allow them to cool. Use a deep socket that protects the case from the base to the shoulder-body junction or just slightly above. Install the socket on the drill and set the drill to the slowest speed. A battery screwdriver works very well for this. Insert the case with the neck exposed. Light a propane torch. Turn the lights down in the room until it is easy to see the case neck start to glow red. Start the drill, and use the torch to heat the case neck from the shoulder junction to the end where you trim it. As soon as the case starts to glow at all (it will be a very dull red), its time to remove the case from the flame. Dump the case out of the socket and put a new one in. Repeat.
Annealing your cases will make the brass soft and pliable. Do not allow the heat to travel below the body-shoulder junction to prevent softening parts of the case that should not be soft. If you first prepare the case necks by trimming or reaming, and trimming to length, and neck sizing, then annealing you will get very uniform neck tension and bullet release. Your cases should last nearly indefinitely. You can anneal between every reloading or as infrequently as once every 10-20 loading's maybe. I've come to the conclusion that annealing between every reloading doesn't hurt anything, and makes it easy to keep track of what you should be doing.
See Case Annealing in this document
There are two major methods of improving primer pockets, and two reasons for doing so.
Military surplus brass has had the primers crimped into place. When these cases are deprimed there remains a ring that interferes with primer insertion, and the diameter of the primer pocket may be a little too small at the top. To correct this, a primer pocket swager is used to force the correct dimensions by brute force. A tiny amount of Imperial Die Wax (which should be a staple on your reloading bench) helps keep the force down, and the surface finish up.
Preferred tool: RCBS Primer Pocket Swager Combo
This tool can also double as a stuck case remover with the addition of
a 1/4-20 bolt and 1/4-20 tap. This is one of those operations
that require a strong press. If you use this on a weak press, you
run the chance of damaging the press alignment. There are several
standalone primer swager tools.
In all but the most expensive of cases, the primer flash hole is formed by a punch. This leaves the inside of the case at the top of the flash hole very ragged with waste brass. A small pilot drill is used to chamfer the top of the flash hole to clean it up. The idea is that when the primer detonates the hot gas and primer material will enter the powder chamber the same way for each case, thereby causing uniform ignition. As a theory it sounds good, the work is easy to perform and you only do it to the case once. What's to loose? (that's my way of saying I have no idea if this makes one bit of difference but my OCD says since I'm already doing everything else I might as well do this and have done with it!)
Preferred tool: K&M Professional Flash Hole Uniformer Comes in 0.080" and 0.062" for large and small rifle primers.
When a case neck is trimmed to length, there will be sharp edges inside and out that need to be chamfered.
If you are loading 'regular' bullets you could use a 'regular' chamfering tool, but if you plan to load any boat tail bullet it is better to use a chamfering tool with a shallower angle to match the shape of the base of the bullet. The shallower angle will not interfere with loading 'regular' bullets (with flat bases).
There are a lot of chamfering tools.
One day when I'm rich and famous, I'm going to get the K&M
set. Until then I'm stuck with the Lyman tools. Oddly
K&M doesn't make an outside tool.
Turning your case necks reduces a major accuracy detractor - the variation in neck wall thickness that forces your bullets to be off the center line of the barrel.
Neck Turning is a commitment to both accuracy, and technique to be followed for the life of the cases so treated. Typically a case that has been neck turned will not function correctly in a conventional sizing die of either configuration (FL or Neck) because the neck wall thickness has been altered. Conventional bushing type dies may be used. I recommend using Wilson hand dies with bushings to compliment neck turning.
You will need to have the correct size bushing. You can
calculate the diameter necessary by adding the bullet diameter to the
neck wall thickness twice and subtracting the desired neck tension in
thousandths. For example my 6.5 Creedmoor fires a 0.264"
diameter bullet. My Hornady cases have been turned to 0.014"
average neck wall thickness and I want 0.002" neck tension.
(0.264+(2*0.014))-0.002 = 0.290 bushing diameter.
Actually my case necks are 0.0135" and I want 0.003" tension so
the bushing I want is (0.264+(2*0.0135))-0.003 = 0.288, and that way I
get just a little bit more neck tension.
To reap the benefits of neck turning, start with fired cases that have not been resized in any way. Trim them to length. Measure the neck wall thickness (see above) and determine the average neck wall thickness. Make a note of this dimension to refer to later.
This is a good time to anneal the cases and softer brass helps to make turning easier. (see above)
The first step is to move the neck wall thickness variation to the outside of the case. This is done by forcing an expander into the case neck.
Assemble the three components shown below (Press Adapter shows the Mandrel installed), and install the completed tool into your bench press. Adjust so you can see through the riser's window.
With a Q-Tip apply a very light amount of Imperial Die Wax to
the inside of the case neck.
Screw the depth adjustment screw into the mandrel just enough to
stretch the case neck (notice the taper on the mandrel). Most of
the time, I find the case neck stops well below the top of the ground
Preferred tools: K&M Refer to the K&M Products page at MidwayUSA
Expand all of your case necks.
Assemble your Neck Turning Lathe and back the cutter adjustment off at least 0.002" from the maximum case neck thickness. Be careful not to allow the cutter adjustment to back out of the body, its a double screw arrangement that will drive you nuts trying to reinstall.
Place the lathe pilot into the the lathe. Attach the jack screw assembly and take up the slack. Insert the pilot into the case mouth (it should be a snug fit), and rotate the case under the cutter until you have located the high spot. Gently advance the cutter until it just touches, then back off a few 0.0001's and tighten the cutter. Rotate the case. With luck you will have landed on the correct setting to just kiss the high spot.
The cutter advances 0.002" per revolution. On the body of the lathe there are 5 marks around 180 degrees giving 1/10 revolution indicators, or 0.0002" per mark.
Slowly advance the cutter, tighten the cutter, turn the neck until you have a spot large enough to measure neck wall thickness. From here on you can try a cut, test a measurement to sneak up on the correct setting. Remember - you want to remove no more than 1/2 of the thickness variation for most applications.
Preferred tool: K&M Neck Turning Lathe and accessories
from the K&M Brand page
at MidwayUSA (available elsewhere as well).
Many powders exhibit variations in muzzle velocity that are directly proportional to the ambient temperature, or to the temperature of the ammunition and or the chamber. Some years ago Hodgdon spent some effort on developing powder that now comprise its 'Extreme' line. Other manufacturers have not been so public with their temperature stability. Military snipers develop and use temperature tables for all of their ammunition, and for them it makes a great difference. The military however is not in the handloading business, so the sniper must observe and correct for the effect. As a handloader you can anticipate the effect and compensate for it by component selection, or you can observe it's effect and compensate after the fact. Most powders will generate higher muzzle velocity with warmer conditions - but the occasional powder exhibits an inverted effect. In some powders the difference between warm and cold is enough that if you are developing a hunting load in the summer, it will be all but useless in the winter unless you observe and compensate.
Another place where we need to observe temperature variation could be in some of the measurements we attempt to make that have resolutions smaller than 0.001". Materials change size with temperature significantly. The only thing I want to say about it here, is that when you are neck turning, particularly if you are using a power source to rotate the cutter or the case, you may create enough heat that the result is not to your liking. Light lubrication with sizing wax works wonders.
For this discussion we are going to make several
assumptions. To start with, we are only discussing modern center
fire rifle metallic cartridge reloading. We also assume you
already have a particular rifle and caliber selected. There are
times when power takes priority over accuracy (for example bear
protection loads), we are going to assume you want your rifle and
ammunition to shoot with more accuracy than power so that you can hit
what you are shooting at. If you think you need to increase
power, select a cartridge known for excellent long range performance
and limit yourself to ethical ranges, meaning ranges where you have
proven you make ethical shots. Unlike defensive pistol shooting
where power, accuracy and speed are balanced, we are going to assume
you have all the time in the world to make the shot, and that the
cartridge you have chosen is sufficiently powerful even when using less
than maximum loads. We are going to assume that accuracy is
Quick Load is a computer program that calculates the firing conditions of nearly any cartridge. Quick Load (QL) is commonly used to find the barrel time (Bt) or the length of time it takes the bullet to exit the barrel, muzzle velocity, pressure and many other parameters useful to engineers and forensic analysts. Quick Load is relatively inexpensive, and once calibrated to the specific measurements of your cartridge it makes accurate predictions.
Determine the purpose of this load. Will it be used for target shooting? Hunting? Defense? Offense? Something Else?
Based on the purpose, select what you believe is the appropriate bullet from among all the bullets available to you for your chosen rifle. For hunting you want to consider the species of game animal, maximum range at which you may shoot the animal, and the environment in which you are likely to be shooting. For long range hunting, make sure the bullet you select will be stabilized by the twist rate of your rifle. Berger and JBM Ballistics offer free on-line stability analysis. Once a bullet has been selected ensure you have a sufficient supply of them. Between testing and training you will likely use up 100 bullets pretty quickly. If you plan to use this load for many years, you should also plan to test, verify and train annually.
There are a lot of factors that might be considered when choosing powder, from availability, to price, and shooting characteristics, that are up to you, but the one immutable fact is that you need to select a powder that will work with the cartridge and bullet you have chosen. Powder burning rate is a measure of the relative speed that a particular powder burns in the cartridge and bore. That translates directly into how fast gas is generated and that translates into how much gas can safely be generated while remaining below the bursting strength of the firearm. Reloading manuals are available from a number of sources but component manufacturers and powder manufacturers are the ones with the resources to investigate a wide range of compatible components. Avoid load recipes you find on the internet, although internet sources are useful for cross-checking ideas you are researching, never rely on someone else's load to work equally well in your rifle.
There are a couple of very important ideas to keep in mind when choosing powder for long range shooting.
The first is temperature sensitivity. Some manufacturers have recently introduced temperature stable powder that behaves very much the same over wide variations in ambient temperature, while others (the older powders mostly), exhibit enough sensitivity to powder that loads you get to work well in summer are useless in winter and vise-versa.
The second is how clean the powder burns. You won't find much about this in loading manuals, even those from the manufacturer. There are two undesirable residual effects of firing, carbon and copper. Some powders just burn cleaner than others, and sometimes they don't burn as clean in larger or smaller cartridges The residual carbon accumulates between shots and eventually accuracy deteriorates. I do not know of any powder that appears to burn dirty that continues to be accurate longer than a clean burning powder. Then there is copper fouling. This happens because some of the copper in the bullet jacket is vaporized by the heat of firing and/or heat of friction. The copper gas then condenses onto the inside of the barrel. Sometimes copper is simply scraped off and subsequent shots scrape more copper into the same place in the barrel. Eventually accuracy suffers, and then you suffer while you try to remove the copper fouling. Recently powders have been introduced which contain a 'decoppering agent' and reports indicate the stuff works. So if you expect to take a lot of shots between cleanings you may be better off with a powder that reduces or eliminates copper fouling.
Another consideration is the style of powder. Generally it comes either as a stick or a ball. Both are very small, but the stick shapes are harder to dispense from many charge dispensers. Ball powder packs much tighter into the case, and is likely to be somewhat more difficult to ignite.
The best accuracy loads are nearly always found at more than 90% fill ratio. When you are choosing a powder don't select one that has it's maximum charge at less than 90% of case capacity if possible.
As with bullets, once you have settled on the powder, make sure you have enough to supply your shooting needs. There are 7,000 grains in a pound. If you load 50 grains per shot, each pound will load no more than 140 shots. Powder generally comes in 1 pound and 8 pound containers. If you buy more than one container, try to get containers that have the same lot number. A 'lot' means a manufacturers run where all of the product comes from one batch of components, one setting of the machines, and one testing of the finished product. Some powders exhibit significant changes between lots. Once you understand the information in this book, you will know how to adjust for lot to lot variations, but it is much better if you can just avoid the problem.
Powder should be stored in its original container, and kept in a cool, dry, dark place. Stored that way, powder should last at least the remainder of your lifetime.
As with bullets and powder, you should establish which primer
you are selecting for your load. For rifle primers there are
large and small, standard and magnum, and a recent category addition
'military'. Primers from a variety of manufacturers may
demonstrate variations in the ability to initialize the burning of your
powder. Variations in primer cup thickness and hardness between
manufacturers may demonstrate variations in the ability of the primer
to withstand cartridge loading forces in semi and full automatic
weapons, however these same variations in hardness may also translate
into the quality and/or quantity of the primer's explosion due to the
force of firing pin impact.
When you are researching the load test range (see below), the published information may contain the primer used. In my experience, changing primer manufacturers or style (standard to benchrest for example) creates a little less variation in group size than changing bullet seating depth by a few thousandths. Therefore I recommend you pick a primer similar to the majority of the loading manual suggested primers, and proceed from there to the testing phase. Once you have achieved the best charge weight, and best seating depth if you want to try additional 'uniforming' techniques, you can try changing primers, or case neck tension, both of which affect initial conditions before the bullet leaves the mouth of the case.
Magnum primers are designed to initiate large case volumes, and standard primers do a good job of initiating volumes up to 30-06 and maybe a bit larger.
Keep in mind that the initial conditions inside the case, chamber, throat and bore of your rifle affect the development of pressure, which translates into the rate of bullet acceleration, and muzzle time. You want every shot to behave the same, and the initial process of lighting the powder and generating pressure may not work as planned if the primer explosion generates enough energy to force the bullet into the rifling before the powder starts to burn. That situation creates an excessively large space for the powder to start burning in, which slows the process significantly, and also puts your bullet into a condition requires the highest pressure to overcome the engraving force. Fortunately should this occur, it is likely you will recognize it as a very slight delay between trigger pull and shot/recoil. Sort of a very fast click-bang.
Only a very heavy roll crimp into a bullet cannelure stands a chance of resisting a 'too strong' primer explosion until the burning powder gas production can catch up.
Primers are sensitive to oil such as found in fingerprints. Under no circumstances should you ever handle a primer by bare hand except to throw it away. This is the main reason I always wear Nitrile gloves while reloading. No greasy fingerprints on cases, bullets, or primers. On the cases and bullets it's cosmetic, on the primers it is the difference between works, and doesn't work. Don't allow other grease or oil from the reloading operation anywhere near your primers, or the primer pocket of the case.
Once caveat with regard to primers. If for whatever reason your load demonstrates hang-fires or any noticeable lag between the trigger breaking and the shot occurring then I would suggest you look to your primers first then to your powder.
Using all available sources for your cartridge and bullet, record the suggested starting and maximum charge weights of powder. Summarize the maximum in particular. You may find one or two sources suggest a lower maximum charge than others. If that happens I usually go with the powder manufacturers recommendation for maximum.
You may not want to go as low as the starting charge, unless you
have absolutely no experience with this cartridge, or components.
Experience has taught that the right load will be more than 90% of case
capacity, although you won't see this number published in most loading
manuals. NOTE: See the Initial Physics section for a discussion
about 'Primer Output and Initial Projectile Movement' for more
Subtract the starting load from the maximum load. That's your charge test range. Divide your charge test range by a convenient increment number. I usually use 10 for simplicity. Divide the charge range by the charge increment. For example, in the 308 Winchester, 175g bullet, using Varget powder the manufacturer suggests a starting charge of 42.0 grains and a maximum load of 45.0 grains. If you were to use these figures: 45.0g-42.0g = 3.0g/10 = 0.3g which will be your charge test increment.
To perform an Audette Test, you will load one round with each of the charges in your test range. In the example, one each of 45.0, 45.3, 45.6, 45.9, 46.1 ...
Load several extra at your minimum and maximum load. One goes in with the Audette Test loads, one maximum is to fire first to make sure this load is safe in your rifle, and one or more of the min and max are to make sure you are reasonably zeroed at your Audette target, and have sufficient target coverage for the entire test range.
NOTE: If the following paragraph doesn't make sense, pause here,
and read my discussion on Initial Physics
NOTE: I use 'Ladder Test' and 'Audette' test interchangeably throughout all of these discussions.
Creighton Audette deserves the credit for figuring a lot of this well before finite element analysis computer code, or even electronic chronographs were available.
Since we are trying to launch the bullet near the peak of the
muzzle rise, where slower bullets point higher, and faster bullets
point lower, you may see the slower bullets in the Audette test impact
the target higher than the faster bullets. I suggest you use your
maximum test load to zero your rifle at the range that you will conduct
the ladder test. By testing the maximum test charge for signs of
over pressure (hard extraction, ejector marks, case head expansion,
cratered primers etc.) you will know if you should ever fire that
charge again. By zeroing (using the maximum test charge) at the
ladder test range, you will hopefully keep all of your shots on the
target. We don't yet know for sure, in your test, if the fast
bullets hit higher or lower than the slow bullets, but by anchoring one
end of test string at the middle of the target you should be able to
keep everything on your target. Speaking of targets, I like to
use USPSA cardboard targets for most of my long range testing.
These targets are 18-1/4" wide by 30-1/8" tall, and have a silhouette
shape (head and torso), the front is cardboard brown, and the back is
white so you can select whichever side is more likely to highlight
bullet impacts. I use a Lyman target dot (adhesive orange dot 2",
4", 6" etc) in the center of the USPSA target as an aiming point.
At 300 yards, a 2" target dot is about 0.7 MOA. You could just as
easily use a felt tip pen to make an aiming point. The USPSA
cardboard target is stiff enough to support its self when stapled to a
rigid support on one edge only, but if its windy you may need a bit
more than that.
Here is an example of a 308 Winchester / VARGET / 175 SMK ladder test. You can clearly see that the faster bullets impacted the target lower. From this you may get an idea how you should setup your ladder test target
NOTE: Between shots #10 and #15 in the ladder test below, there was a total change in muzzle velocity of 56 fps which should result in a 1.1" vertical change in point of impact, or about 0.020" per foot per second change in muzzle velocity, with faster shots hitting higher. The impacts don't line up in a straight vertical line evenly spaced out, because the barrel is pointing at a slightly different place at the moment the bullet exits the muzzle due to the vibrations discussed in Initial Physics. The wind appeared calm at the time of this test, but had there been a full value change of 1.0 mph wind it would have moved the impact 0.6 inches left or right for any shot in this series. Shot #14 at 2712 fps striking below each of the three previous (slower) shots, indicates that the muzzle was bending upward higher when the slower shots left the muzzle. This is the velocity variation cancelling effect we are looking for.
In this test the charge range was from 40.5 grains to 41.7 grains. The test increment was 0.2 grains, and 15 rounds were recorded. Note that shot #15 is very close to shot #8. Also note that shots 6,7,8 were close together but completely out of sequence indicating that there was a significant node in this region, however a more desirable node occurs between shots #11 and #14 where muzzle velocities between 2666 fps and 2712 fps (46 fps change) impacted within 0.3 MOA.
In this section we are going to necessarily get into a lot of detail about how to take interior measurements of your chamber.
Here is what you need to understand to achieve accurate measurements:
When measuring loaded rounds we will refer seating depth to the distance from the case base to the bullet ogive as CBTO. Keeping in mind that the extractor is likely to hold the case head against the breach, the true zero jump is typically found at CBTO + 0.002" = BFTL for a fired then neck sized case. Full length resizing that 'bumps' the shoulder back must be adjusted so that CBTO + 0.007" <= BFTL or else case head separation at firing is likely to occur. In other words, do not bump the shoulder any more than 0.007" (for 308 and 30-06 cases. Check SAAMI specifications as described above for others).
Many will tell you that best accuracy occurs when the bullet has
zero jump, or is jammed into the rifling. This may be more about
getting the cartridge into
alignment with the bore than anything else. When the bullet touches the rifling, your headspace starts to be controlled by the bullet, and closing the breach may well force the case into better alignment. Proper headspacing, to align the case body without using any force on the bullet is critical to best accuracy at all shorter seating depths.
Seating your bullet to achieve zero jump seems most likely to generate the highest pressure for a given load, however, according to Quick Load using the 308 example above, the round with the bullet furthest into the case (biggest jump) generates the most pressure. This is due to the smaller initial volume for the gas expand into. I think that may be true however Quick Load does not know the distance to the rifling, so it assumes there is an equal force required to overcome bullet inertia, neck tension, engrave the bullet to the rifling and start the bullet rotating for all cases. It does seem that a bullet given a running start before encountering rifling would present less resistance, but you need to remember the scale of energies involved, and that difference between "dead lift" and "running start" while it appears substantial, may well be insignificant when compared to the force created by chamber pressure. Personally I think zero jump may increase the rate of initial pressure rise and may help to stabilize maximum pressure time, both beneficial to low muzzle velocity variation.
In the Quick Load prediction for the 308 test with the bullet seated furthest out (to zero jump in my rifle) at 2.879 COAL (Cartridge Over All Length) the MV is 2676 at 52,842 psi. For each 0.010" the bullet is seated deeper into the case, the velocity rises by an average of 3.83 fps, and pressure increases by an average of 416 psi. Most importantly however the Barrel Time decreases by an average of 3.8 Milliseconds (mS). Measured MV averaged 3.0 fps faster per 0.010" deeper seating.
Seating a bullet far enough out to touch the rifling in some firearms will make the bullet too long to work through the magazine or the action. Seating the bullet just a tiny fraction further out may cause the bullet to stick in the barrel if a round is unloaded, leaving you with a mess of unburned powder throughout your action and probably preventing you from loading or firing the next round.
For hunters, competitive marksmen and tactical operators magazine function is critical so they would start testing at the maximum COAL that will work reliably in their magazine. Some hunters and marksmen using single shot rifles will want to start with the bullet touching the rifling.
Now that we know all this, I believe the best way to perform an Audette Test is to seat the bullet at the maximum COAL that you will use.
In order to make the adjustments to your bullet seating die, you
need to know the interior dimensions of your rifle's chamber. In
particular, you need to know the distance from the breach face (bolt
face) to the origin of rifling. When we talk about bore diameter,
we are referring to the diameter of the lands not the groves. The
nose shape of your selected bullet puts the location where the bullet
diameter is equal to the bore diameter somewhere between the nose and
it's maximum diameter. It is that point from which all meaningful
measurements must be taken. This point may be found by inserting
the point of your selected bullet squarely into a hole exactly equal to
the bore diameter. In fact a useful measurement may be taken by
using a hole only somewhat equal to the bore diameter provided that
this exact same hole is always used for this measurement of this bore
and bullet. In other words, there is enough difference in
dimensional tolerance between measuring tools that you should only have
one tool to use for all of your measurements. If you want to
relate your measurements to someone else they must calibrate their tool
to yours. Have them measure one of your bullets, cases or loaded
rounds, where you have supplied your measured values. They can
then determine the difference between your tool and theirs and apply
that information where necessary to achieve similar results. To
complicate matters even further the area of your chamber called the
leade transitions into the rifled bore with a structure known as the
forcing cone, a chamfer at the beginning of the rifled bore. Your
bullets nose shape intersects the forcing cone at some point which is
determined by the slope of the cone and the slope of the bullet nose.
To find the interior dimension (breach to lands) several tools have been introduced. My personal favorite was a dummy round that comes with the RCBS Precision Micrometer kit. The dummy bullet is steel, and has a fairly rapid transition to the maximum diameter which helps keep it from sticking in the barrel. However I have found it necessary to lightly lubricate the dummy bullet nose on many occasions. The dummy cartridge body is designed to allow the dummy bullet to side in and out, and a tension adjustment screw allows for a convenient 'just right' setting. The dummy cartridge head however is not the same shape as a normal cartridge case head and sometimes requires a bit of finesse To use the RCBS tool, the dummy bullet is pulled out of the dummy case enough that it must be too long, the dummy round is inserted into the action (hooked under the extractor and pushed against the ejector) and the action is gently and fully closed, forcing the dummy bullet into the dummy case. If care is taken to ease the action closed the reading will be very accurate and consistent. In push feed bolt action rifles, the extractor and ejector can alter the reading. The extractor requires a push on the bolt to snap over the cartridge rim, and can push the dummy bullet too far into the dummy case. The ejector places a strong sideways thrust onto the cartridge to ensure the case snaps out of the action as soon as possible. In controlled round actions (Mauser) the extractor must pick the case rim up from the magazine - it doesn't snap over the rim very well. The ejector however does not affect the dummy round.
In a push-feed action; with the bolt open and the muzzle pointed upward, place the rim of the dummy case head under the extractor, this may require the use of a tool like an allen wrench to help hold the case head under the extractor while you use a finger to press the dummy round into line with chamber against ejector pressure. Carefully move the bolt forward while holding the dummy round in line as long as possible, then carefully close the bolt fully to squeeze the dummy round to exactly the length between the bolt face and the origin of the rifling. Carefully open the bolt and retrieve the dummy round without letting it be forcefully ejected. With a little practice this is quick and easy to do.
The second step is to measure the distance from the dummy round case head to the dummy round bullet at the diameter of the bore. This can be accomplished with the supplied RCBS tool, but I have found that for this measurement a set of adapters for a dial or digital caliper jaw are far superior. Hornady makes such a tool and with one simple modification it is as perfect a tool as I've ever used for this purpose.
The jaw adapter is installed on your calipers, and an adapter with a hole diameter of approximately your bore diameter is installed in it so that the bullet nose can be inserted in the hole, and the distance from that point on the dummy or real bullet to the case base is read on the caliper. This is one place a digital caliper really becomes useful because it can be zeroed with the jaws closed on all these adapters, and then provide you with a direct measurement. Otherwise you've got some subtracting to do.
The modification I mentioned is to the anvil jaw adapter which as it comes from the factory is just a flat surface a bit larger than most case heads. I found that fired primers often had ridges around the firing pin impact that changed the readings using this anvil by several thousandths of an inch. Using the bare jaw, the caliper still 'sees' the ridges. To correct the problem, I took a 1/4 inch washer that appeared to be fairly flat, drilled out the center a bit so it is larger than any primer, then stoned it flat on a coarse diamond bench stone on both sides, and tested it with a micrometer to ensure its sides are parallel. Then I stuck the washer onto the center of the anvil with double sided tape. Its been on there working perfectly for over a year now. And yes that adapter is easily zeroed out too. Now I get very consistent readings on cases regardless if fired, primed, sized or loaded.
A last quick note about the Hornady adapter. They also provide holes sized for cartridge case shoulders allowing you to take precise CBTD (Case Base To Datum) readings, to use while adjusting your dies to minimally work the case for much better fit and longevity.
Another tool that you could use is called a 'bullet comparator'. It is a block of aluminum or steel that has holes drilled through each side for various caliber bore diameters. The block is often just 1.000" from side to side regardless which side, simplifying your calibration. It is used the same way, by placing the bullet end into the appropriate hole and measuring the length, the subtracting the length of the comparator
Hornady and others have introduced a tool which uses a cartridge case on a push rod to position a case and a bullet in the chamber, extend the bullet until resistance is felt, then lock the bullet push rod in place to facilitate measurement. This tool can not give you an accurate measurement to the bolt face, but it can give you an accurate measurement from the bullet ogive to the case shoulder datum line. Keep in mind that the modified cartridge case supplied with the tool was not fired in your chamber, so its headspace relationship can be in the range 0.003" to 0.007" different than your actual headspace. One way to fix the problem is to make your own modified case from one fired in your chamber. Another is to measure the CBTD of the modified case, and a fired case to calibrate the modified case to your chamber. It is necessary to calibrate the supplied 'modified case' to your fired (and resized case) so that you can use the resulting measurements to accurately measure and adjust loaded rounds. In all cases remember that a case fired in your chamber will shrink in length so it is not a perfect measurement, but might be within 0.002" or so. Also please note that the instructions that come with the Hornady Lock-N-Load OAL gauge appear to exhibit a fundamental flaw in understanding how the comparator works. Variations in bullet nose shapes between different types of bullets do move their datum line (point where the bullet diameter equals bore diameter) forward and backward with respect to your reference bullet, however it is that very datum line we are measuring, and the amount of bullet nose protruding forward of the datum line is only important to magazine function. The RCBS (and other) dummy bullets may have very abrupt nose shapes but that ensures the datum line is consistent. Unlike the Lock-N-Load dummy rounds the RCBS tool reads from the breach face. There is no 'source of error' due to nose shape. Ever.
Others have used the idea of a rod inserted in the bore from the muzzle to find the position of the bullet in the chamber. This measurement technique can produce accurate and repeatable results, for BFTL. Since the case is forced back toward the bolt face during measurement, this technique can not accurately utilize the shoulder datum as a reference point potentially introducing errors up to 0.007". This technique must NEVER be used on loaded ammunition.
Because as I showed you earlier on, a difference of just 0.010" can cause a significant change in velocity, pressure and barrel time, your measurements must be consistently accurate to 0.001" to be meaningful.
One last note; The RCBS Precision Mic dummy bullet will give Breach Face To Origin of Rifling measurements in any type of action be it bolt, falling block, break open or anything else. The Hornady tool discussed above can make its measurement in many action types, but has one continuous disadvantage in that you can never close the action on the tool, thus the measurement is Case Head To Origin Of Lands, referenced off of the case datum line, and you need to add in the Headspace for the test cartridge case to get Breach Face To Origin of Lands. Or you can just forget about the roughly 0.002" headspace of a fired case and go with Case Head To Origin Of Lands all the time. Just realize the measurement (using bottle neck cases) will be based on the case shoulder datum line rather than the breach face (case head + spring back). Make sure your case actually enters the chamber all the way. Often the extractor will hold the case head against the bolt and the case shoulder may be out of contact with the chamber. In break open rifles i.e. T/C Contenders and Encores remove the extractor to make the measurement.
Having defined the test charge range, and increment, load one round with each charge.
Having determined the dimension for a zero jump bullet seating depth, choose the minimum seating depth (maximum length) that you will use. If you are using a magazine it will be the maximum length that feeds reliably from that magazine. Otherwise either zero or 0.010" jump is appropriate.
Seat all test rounds to the same depth.
Load a few fouling rounds with the maximum charge used in the test. Use these rounds to foul and zero your rifle just prior to the test.
Setup a large target. I use IDPA target with a 2" aiming point about 3/4 of the way up from the bottom. The aiming point must be visible at 300 yards, and not too large to aim at accurately. The right size will depend on your sights more than anything. Make sure there are no holes in your target (that haven't been pasted).
Place the target at 300 yards from your firing point.
Place a fouling and zeroing target at the same range near your test target.
Using the fouling and zeroing rounds adjust your sights until you are hitting near your aiming point with the maximum test load charge.
Now that the rifle is warmed up, and the barrel is fouled, fire each of the test rounds in charge increment sequence at your test target. Always aim at your aiming point regardless where the rounds strike. As you fire each round record its position on the target. This is critical. You MUST know the charge that resulted in each hole in the target.
Number or otherwise mark each hole once you have retrieved your target.
There will be vertical stringing of your shots. Ok, I had one test with a Ruger SR-556 in 5.56 NATO that clustered all 10 shots in one ragged hole in this test. I think that must be due to the very short stiff barrel. It means that I can load nearly anything in that rifle and it will shoot where I point it.
Back to the test. Recall how in Initial Physics I described the motion of the barrel with the muzzle pointing away from the centerline of the barrel while the bullet is still inside the bore? You just mapped that motion in your barrel over the time between the shortest and longest barrel times in your test. By 'mapped' I mean your barrel was vibrating around the same way for each shot, but each shot took a little bit different time to get out of the muzzle, so each shot 'points to' where the muzzle was pointed at that moment. If you connect the shots with a line, and smooth it out, you probably will get a very accurate map of your muzzle vibration.
What we are interested in is just one part of that map. The part where two or more shots hit at nearly the same elevation, or even better where several shots hit close together. These points on your muzzle map indicate the times when the sum of the vibrations is lowest. Since the vertical vibration has the greatest amplitude, selecting shots at the same elevation regardless of horizontal separation should locate the charge (hence the pressure, velocity or barrel time) that causes the bullet to exit when the vertical vibration is moving slowest. Having a hard time with that? Any vibration in a single plane must come to rest at some point before reversing direction. We are looking for that point.
Find the middle of the charges that resulted in vertically close impacts. This is the charge you will use from now on with these components.
As I showed you previously changing seating depth changes pressure, velocity and barrel time. By testing changes in seating depth you should find that your groups shrink dramatically at one or more depths.
I use 5 shot groups for all of my group testing, but 3 shot groups might be adequate for initial testing.
Using the selected charge from the Audette Test, load however many you are going to use for each group by seating depth.
Having started at the maximum COAL you will use, you only need to seat bullets deeper for each test. I typically run the first seating depth test from the Audette Test depth to an additional 0.060" by 0.010". However some bullet nose types (Berger VLD's for example) have a defined range of 'sweet spots' - see manufacturer for more information.
Clean your rifle. After the Audette Test the rifle is to dirty to complete the group testing without cleaning which will alter results. Fire 3 to 5 shots to zero at 100 yards, and foul your rifle Don't shoot more than about 30 more shots before cleaning and re-fouling while group testing. It helps to zero your rifle so the impact point is about 1" high so you don't obliterate your aiming point in the following tests.
With the rifle warmed up and fouled, at 100 yards fire each seating depth at its own target. One of these targets should exhibit a significantly smaller group than the others, and if you are lucky the targets before and after that one will be only slightly larger with a clear indication that group size is shrinking as seating depth approaches the best group. With that information you may be able to determine that a second seating depth test with increments of 0.003" would be useful to determine the very best seating depth.
The '6.5 Guys' youtube video describing their method of working up loads describes looking for flat spots in the velocity curve between test charges. They observed that the SD (Standard Deviation) of the shots falling on these flat spots was lower than the other shots in their test. In working up a load for my 6.5 Creedmoor I encountered a similar situation where group size was not changing with seating depth enough to make a determination, but the SD for 3 shot groups was an obvious indicator. When I located one seating depth with a very low SD, I set 5 additional shots to the same CBTO and found the low SD to be repeatable, and group size was acceptable. For long range shooting downrange performance can be affected more by velocity variation than by shot dispersion, so 'good' groups at 'single digit' SD's may be preferable to 'excellent' groups with 'double digit' SD's.
From your best seating depth group determine the inherent accuracy of this load in that rifle in terms of MOA. Measure the center to center distance of the widest shots in the group. For our purposes 1.000" = 1 MOA at 100 yards. If you want to use more precision 1.047" = 1 MOA at 100 yards. Knowing the MOA capability of your load allows you to predict its performance at other ranges. For example if you made a 1 MOA group at 100 yards (1 inch) then at 300 yards you should be able to shoot a 3 inch group. If you made a 3/4 MOA group at 100 yds, then you should expect about 0.75 X 3 = 2.25 inches.
Now that you have established the best charge weight and seating depth for your selected components, and know about what group size to expect at longer range confirm that your load is 'pressure tolerant' (or velocity or barrel time tolerant), by loading one round with the chosen charge, and one round with 0.1g more and another with 0.1g less powder. Seat all three bullets to the chosen seating depth.
Fire a group at 300 yards with these three test rounds. In the vast majority of cases, all three shots will strike inside the inherent accuracy of this load in your rifle.
Congratulations, you have just found "The Right Load" in 10 shots for the Audette Test, and 21 or 35 shots for the Seating Depth Test a total of at most 45 test shots and a few zeroing and fouling shots, while a lot of your friends may have fired hundreds of shots randomly seeking 'good groups'. With the information you have collected in your first test, you may be able to cut the range of test charges, and seating depth test if you choose to change components, allowing you to develop loads quickly and efficiently when sources of your favorite components dry up, or new components become available.Return to top
As you look at the bewildering array of available calibers,
cartridges and bullets you may not be aware that nearly all were the
result of shooters not much different than you, who wanted something
'special'. Manufacturing a brass cartridge case from scratch is
much to complex and expensive for hobby or experimental
reloading. Since there are so many different case designs already
in factory production, it is very common to use an existing cartridge
case as the starting point for a new idea. When you design a new
cartridge the process is called 'wildcatting' and the resulting
cartridge is called a 'wildcat'. One of the simplest wildcat
operations is to change the neck diameter of a factory cartridge to
accommodate a different bullet. For example the 25-06 was created
by Charles Newton in 1912 by changing the neck of a 30-06 to accept 25
caliber bullets. The 25-06 was released as a factory round by
Remington in 1969. There are a number of case forming operations
you can perform with a good 'O' style press.
Bryan Litz of Applied Ballistics has made both a video and a document covering the Tall Target Test. You should start by reviewing both.
When you mount a tactical scope on a precision rifle, you expect to be able to make sighting corrections that accurately place your rounds on target at long range. Here are the steps to ensure you have correctly performed the work:
Select a mount - precision rifles typically use MIL-STD-1913 or 'Picatinny'
rail. Such rails come in various configurations providing
from zero (0) to at least 30 MOA (Minutes of Angle) slope to enable
scope adjustment for long distance shooting. Typically 20 MOA is
sufficient for most sporting calibers, while 30 MOA is typically
reserved for large calibers and extreme long range.
Select a scope - tactical scopes have easily adjusted elevation
and windage knobs, and probably will have a parallax adjustment.
1 inch (25mm) scopes have less vertical adjustment range than 30mm or
35mm tube scope.
Select a level that mounts to your scope body. Levels that
attach to your rifle only tell you the rifle is level, and are not
appropriate for precision rifles because they can not be ajusted to
match the scope reticle.
Review the Tall Target Test video and document
NOTE: The Tall Target Test can be performed while you are breaking in a new rifle barrel. Read Rifle Cleaning Protocol
Assemble a target with sufficient height to contain both the aiming point and a bullet fired with the maximum vertical elevation your scope can produce from the aiming point.
NOTE: Scope manufacturers list the total elevation adjustment, it is up to you to mount your scope in such a way as to maximize the use of that range. For long range shooting, typically a 20 MOA rail is used to tip the front of the scope down by 20 Minutes of Arc, moving your 100 yard zero to the lower 1/3 of the scope adjustment range, and maximizing the available upward adjustment. For example, the Vortex HS LR 6-24x50 FFP XLR moa scope has a total of 65 MOA vertical adjustment, and 40 MOA of total windage adjustment. From the factory, the scope is set at the mid point where there is about 32 MOA up and 32 MOA down, 20 MOA left, and 20 MOA right. When placed on a 20 MOA rail and zeroed (if all else is in alignment) there will then be about 52 MOA up, 12 MOA down, and still have 20 MOA each left and right.
If your scope has 30 MOA up adjustment you'll need a target about 36" tall, for the 52 MOA in the example above, a 4' target is too small, and going all the way to an 6' target is probably the easiest as 54.4" will be required if everything is working correctly, perhaps more if not.
Your target needs to have enough room below the bottom and above the top to capture any groups or shots that are misplaced, probably 6"-12" is sufficient.
Your tall target should be placed on a backer that has a true straight edge, and that edge should be dead vertical as measured by a long construction level. The line down the middle of the tall target should also be measured vertical.
Before you zero your rifle and complete your scope installation, you have one adjustment remaining, calibrating the elevation control to the fall of gravity.
You will need a regular target to establish zero.
Make sure the bottom of the target is far enough above the grass that you can easily see the aiming point.
There are a couple of additional tests you can do while you have this setup in place.
Keep the record of your Tall Target Test in your DOPE book. Well documented pictures are useful too.
Return to top
Return to top
Your new precision rifle comes from the factory after being fabricated and tested. Depending on the factory, and the order specifications for your rifle, it may have had the bore cleaned and a thick protective coating of Cosmoline, oil, or machine coolant . In any case, it is in the best interest of barrel life, that your first act upon receiving a new rifle (from any source) is to clean and inspect the barrel.
Initial cleaning to remove factory coatings may be accomplished by plugging the barrel at the muzzle end, placing the rifle muzzle down (on a drip pan), and spraying a lot of WD-40 into the chamber end. Leave the WD-40 to dissolve anything left over from machining in the barrel for 10 minutes, then drain and wipe out with a cleaning rod and patches.
One of the challenges of cleaning a rifle is to not get cleaning solvent into places it doesn't belong. One of the best methods I've found to do that is to purchase the appropriate 'Possum Hollow' bore guide and solvent port adapter. Once installed this bore guide keeps everything out of the chamber, and everywhere else that isn't the bore. You'll want to clean the chamber separately.
NOTE: Cleaning using long shoe string style tools is perhaps useful in some environments, and for some pursuits. In my opinion, it is not appropriate for precision rifle cleaning, and should never be used in precision barrels except as a last resort.
NOTE: Cleaning rods come in a wide range of styles. For precision barrels, steel rods are out because steel is hard enough to destroy the interior of the barrel. Brass is softer, yet it to can damage the barrel if misused repeatedly. This leaves us with coated rods and carbon rods. I prefer Gunslick Carbon rods and their brass rifle jags. I do not find any reason not to use J. Dewy rods, however read their disclaimers about corrosion and fitting. Both style rod come equipped with a ball bearing handle, which I prefer. J. Dewy has a line of jags and tips that do not react to the chemicals typically used to remove copper, so they don't produce a false positive reading, which you sometimes get from a brass jag.
NOTE: Cleaning patches from Montana Extreme seem to me to be the top of the line for use in precision rifle barrels, and there's nothing wrong with their cleaning rods as they are coated.
NOTE: Cleaning Solvents from KG Coatings are useful because they are specific for Copper or Carbon. Few of the mainstream manufacturers listed above have differentiated solvents. It is important to be able to remove only Carbon and leave Copper intact in the barrel. KG-1 Carbon remove does just that. It is difficult to remove Copper without damaging the barrel. KG-12 removes Copper without any chance of damage to the bore.
NOTE: Gun oil (KG-410) is a fine oil for protecting and lubricating as necessary however, I have found MILTECH-1 Weapons Lubricant lives up to its advertising, and is extremely useful as a bore conditioner.
Some folks believe the best accuracy can be obtained by cleaning everything out of a barrel as often as possible. This philosophy has won bench rest competitions, but is not practical for weapons used in the real world where many shots are fired between cleanings. Our challenge is to analyze what occurs inside the barrel with the first shot, and subsequent shots, and why accuracy falls off over time if the bore is not cleaned, and what to remove, and when.
As the bullet moves into the barrel, pressure rises to its maximum typically within the first 6 inches of travel. At this point the temperature has also reached maximum and there is still a lot of unburned powder being accelerated down the barrel. The bullet jacket has been forced into the rifling and the bullet is beginning to accelerate very quickly. The hell that exists inside the chamber and first few inches of the barrel is so intense that it will erode the machining, and leave the surface of the barrel checked and crazed. There is little that cleaning can do to alter this condition, nor prolong its useful lifetime.
As the bullet moves further along the barrel pressure and temperature of the gas drops quickly and significantly to the point it no longer poses a threat to the barrel material or machining. Bullet velocity has increased substantially, and now jacket material is melted and pressed into whatever irregularities exist, particularly onto the lands (raised surface of the rifling), and the corners of the bottom of the grooves, and machining marks along the bottom of the grooves.
As the bullet continues to accelerate in the last 1/3 of the barrel, it reaches its maximum velocity, and the frictional heating of the jacket is at maximum. This is the area most likely to see heavy copper plating.
When the bullet exits the barrel, the gas and residual debris are ejected at a speed much greater than the bullet, but some of the debris nearly always remains in the barrel. This material is mostly carbon.
When the next shot is fired, whatever carbon is left in the barrel is pounded into the barrel by the bullet, or is ejected ahead of the bullet. Given the very acute angle between the bullet ogive and the barrel, a lot of the carbon is trapped and pounded into the barrel walls. Some of the copper that is deposited by this shot will have a carbon layer under it, and some will find either bare steel, or previously deposited copper to adhere to.
When subsequent shots are fired, whatever material that can move is ejected ahead and behind the bullet, and the remaining material is again pounded into the walls of the barrel. Copper continues to adhere, mostly to locations where it has begun to plate the surface.
As the first shot is fired, a certain resistance to the bullets movement down the barrel occurs.
As the second and sometimes a few more shots are fired, each experiences a slight increase or decrease in resistance to movement as a function of the lubricity of the material previously deposited in the barrel, and the changes in that materials distribution.
At some point an equilibrium is established where each subsequent shot feels essentially the same degree of resistance to movement, and at that point muzzle velocity variation is reduced, and accuracy begins to occur.
This condition will persist typically until carbon buildup causes a loss of accuracy, which in my 6.5 Creedmoor H4350 load has been found to be at about 300 round intervals. In my 308 Winchester Varget load, the interval is closer to 400 rounds or more. In my 204 Ruger Varget load, the interval is about 100 rounds. In my SR556 CFE223 load the interval seems to be greater than 500 rounds. From this I conclude that the available surface area of the barrel and the carbon debris load of the powder are the controlling factors determining when accuracy is degraded and how often a carbon cleaning is required.
To restore accuracy when carbon fouling has degraded it, all that is required is to run a carbon specific cleaning cycle. I use a nylon brush of the appropriate size, soaked with a few drops of KG1 and quickly run the brush all the way down the barrel and out the muzzle, then back into the bore guide body for a count of 1. I repeat to a count of 25 as quickly as is practical (KG1 is designed to work best when agitated this way). Then I run a patch soaked with KG1 through and out the muzzle. This patch will be extremely dirty. I repeat the KG1 patch one more time, this patch is almost clean, so I repeat again and the 3rd patch usually comes out with no carbon at all. At this point I wet a patch with MILTECH1 and scrub the barrel in 4" sections from end to end to ensure the MILTECH1 is reaching into all available spaces. Next I make a point to fire the barrel 3 shots before I put it away to get the MILTECH1 up to operating temperature, and to season the barrel for the next cold bore shot. This is probably me being OCD, because typically those three shots all go into the same hole.
I am totally convinced that the MILTECH1 routine inside the barrel has stabilized the accretion of copper and distribution of carbon in such a way that it has made the barrel generate more uniform velocity. I'm also convinced the MILTECH1 is responsible for the extremely fast carbon cleaning cycle.
Carbon cleaning cycles are so quick and easy I carry the required material in the gun case, and can do one of these anywhere, anytime in just a few minutes.
At some point in the future, a carbon cleaning cycle will not restore accuracy to the customary 0.25 MOA, and I will decide it is time to do a copper cleaning cycle, which goes like this;
First do a carbon cycle but omit the MILTECH1 finish.
Perform the same nylon brush treatment using KG12 and 25 strokes followed by KG12 soaked patches. Watch the patches for blue streaks which are dissolved copper. Repeat the KG12 brush routine followed by the KG12 patches until no streaks are present. Follow the KG12 routine with a degreasing using brake cleaner soaked patches and/or rinsing the bore with brake cleaner. After degreasing, MILTECH1 the bore, and wipe KG4 Gun Oil liberally on all other surfaces. KG4 can be left on for storage. Put a note on the rifle to MILTECH1 again, and perform a break-in cycle before next use.
Copper cleaning cycles generally involve more material than I carry with the rifle, and typically are not as critical to be able to perform in the field, so they are accomplished back in the shop at home.
Clean the bore. Clean it to bare metal using the Copper cycle with degreasing and finish with MILTECH1.
Return to top
Leg carrier in use
Leg carrier detail
Since I built the shooting bench to
transport on my UTV, I've sold the UTV and bought a Hummer H3 ... and
installed a long roof rack.
The bench with it's legs easily fits inside the roof rack, along with two or three of the Portable Target Stands (below). Pictures when I think about it.
While the bench was onboard the UTV over the winter rain caused the leg's threaded segments to rust. I wire brushed the threads put lithium grease on all of the threads. That corrected the rusting problem and made the legs easier to install and remove, but the grease wanted to get all over everything. I put threaded PVC pipe caps on the legs to act as thread protectors and to protect everything else from the grease. So far it's working, just have to keep track of the caps when the bench is deployed.
The concept for this target hanger is that it be inexpensive, easy to build, portable in my UTV, a pickup, or the roof rack of my HUMMER H3, man portable from where ever the closest road is, across broken ground filled with badger holes, sage brush, etc. and that it supports up to a 12"x3/8" AR500 target, and holds up to 308 impacts from 100 yards out with the smaller AR500 targets (maximum energy transfer to the hanger).
The hanger is made from two 10' lengths of 1/2" rebar, a couple inch long pieces of drill rod, a couple of pieces of (pick one; galvanized pipe, plastic pipe, copper pipe) with inside diameter of 1" or preferably just slightly larger. The length of the pipe is not critical. There are two considerations. If the pipe is tight on your rebar you may need to be able to get a good grip on the pipe to futz it around until the legs open or close. If your bends are not tight, a short length of pipe might be able to work its way around the bend and become lost in transit, disabling the target hanger. Should this happen, you can make a field repair with anything from shoe laces to paracord, or duct tape.
When I built the first of these hangers I though it would be easy to heat the rebar to a temperature at which I could bend it by hand. Propane wasn't hot enough. MAPGAS took about 30 minutes to heat to bending. I didn't want to buy acetylene just for this, so I started looking at cold bending and came up with a simple and inexpensive way to do it.
If you do use heat, you can get nice tight bends fairly easily, and without any tools. You will have to pay attention to get the second bend in line with the first bend, and I found it useful to stick a couple of pieces of scrap wood together as a makeshift angle gauge to keep the bends uniform. You'll also have to pay attention if using PVC couplings for the hinges to make sure you don't melt them!
If you are going to cold bend, you need a forged eye-bolt and a 3' or longer piece of pipe large enough to contain the rebar. I used 1" black iron pipe. The eye-bolt needs to be forged to be strong enough to work. Then you need a length of 4x4 or equivalent to mount the bolt. Mine is 3' long. There is a stack of washers (fender then regular) under the nut to distribute the load on the 4x4. The jig can benefit from an accessory clamp to hold the rebar in position, and resist slippage and twisting, or you can do like I did and just use your foot. If you do use your foot (or someone else's foot), really bear down to keep the rebar from slipping. I recommend you make up a 'V Block' that can be clamped tight enough to resist slipping and twisting. Something very similar to a gunsmith's barrel vise. When I get mine done, I'll post an update.
Here's a picture of my current 'bending kit'.
In the future I will recess the eye-bolt washers and nut to get the back of the jig flat, and install a 'V' block clamping arrangement to tightly secure the rebar for bending.
And a closeup of the forged eye-bolt.
Measure and mark the first 10' rebar at 4' from each
end. This will leave a 2' wide top (hanger) run.
Measure and mark the second 10' rebar at 4' 0-1/2" from each end. The second leg's top run will be 1' 11" leaving just enough clearance for the legs to fold flat.
Insert the rebar into the eye-bolt and advance it to the bending mark. Slip the bending pipe over the 4' leg and while holding the 4x4 on the ground (stand on it) bend the pipe upward to 80 degrees. As you bend, the standing part of the rebar will want to creep toward the eye-bolt. To get a clean bend you need to prevent that with either your weight (all of it!), or a clamp.
Bend one leg of each piece of rebar, and then remove it from the eye-bolt.
Place the two pieces of rebar together with the bent legs on the same side, and roughly aligned. You could tie the bent legs together using a piece of line somewhere near the foot of the leg, if it helps you control the assembly.
Slip two lengths of whatever pipe you chose to use over the long straight section of both pieces of rebar. The pipes becomes the hinges at this point. Push the pipes to the end with the previously bent legs.
Insert one of the unbent legs into the eye-bolt and clamp it to the 4x4 making sure the bent portion of that leg will be in line with the bend you are about to make.
Bend the 3rd leg to 80 degrees and in the same plane as the opposite leg. Remove the leg from the eye-bolt.
Insert the 4th leg, and as you just did, bend to 80 degrees in the same plane as the opposite leg. Remove the leg from the eye-bolt.
Move the hinge pipes to the outside end of the top run. Unfold the legs to setup the hanger. If everything is working correctly, you are ready to weld chain studs onto the top run.
I use a welding magnet to hold a 1" length of drill rod (sized to fit inside whatever chain I'm using to support the target. In my case 3/16") at 90 degrees (left/right) and parallel to the leg its welded to, so that when folded flat the stud is not sticking up at an odd angle.
Place the chain stud a convenient distance away from the end of the hinge pipe and weld it in place.
NOTE: On the next one I build I'm thinking about drilling a pocket for the chain stud. I'm also thinking of preparing the rebar by grinding off the 'texture' for about 4" toward center from each leg to allow the hinge to rotate easily, and make drilling the stud pocket easier.
Here's what a finished hinge should look like
I have found that looping the chain over the top run once and then dropping a link over the stud is all that's needed to support the target during the most energetic impacts. It may be slightly more stable if you pass the chain from the shooter side over the top, rather than as shown in the next picture. I believe the chain in the picture will go loose in a hit, and wrapped the opposite way it will tighten.
Here's a picture of the completed target hanger.
And some of the targets I use with these hangers.
Targets are AR500 shapes suspended by chain. The bolts are inserted from the front, pass through the chain and have a fender washer an nylock nut to hold the target to the chain loosely. This arrangement cause the target to lean slightly toward the ground which helps with splatter control. Using a grade 6 bolt will slow down splatter erosion, using a carriage style bolt head will do the same.
All Shooting List Emails ...