Many factors are involved in shooting any long gun accurately. One which is not well understood by many shooters, and to which too little attention is paid by most of us, is the fit of the gun to the shooter. Since we don't usually have an opportunity to choose between different stock configurations, but must accept the gun as it was built, we tend not to give much thought to what is involved in gun fit, we just shoot what we have.
It's not nearly as complicated as casual consideration would lead us to believe. The various factors involved are easily understood, and every shooter of long guns should be on speaking terms with them. A few definitions seem appropriate to the discussion.
In the diagram, the dashed line extending from front sight to "C" is the line of sight. The heel and toe of the butt of the stock are indicated, as is the butt, with butt plate. Let's consider the measurements shown, and give them some thought.
If a perpendicular is dropped from the line of sight down to the point of the comb of the stock, as indicated at "B-B", that distance is called the 'drop at comb'. This is probably the most critical of all the factors involving fit. It is at the point of the comb that our cheek rests while sighting. If this distance is right, then when we "spot weld" our cheek on it, our eye falls naturally in line with the sights. We can throw the gun to our shoulder for a quick shot and not have to readjust the position before firing. It is obvious that this measurement is extremely important on a shotgun stock, or any long gun with no rear sight. The drop at comb IS the rear sight. If the comb is too high, the eye is forced high, also, and we will tend to shoot high. To counteract this tendency, we mash our cheek too hard against the stock, trying to lower the eye. This isn't a comfortable, natural way to aim, and, in addition, will lead to our being smacked hard in the cheek from the recoil of the gun. If the comb is too low, the eye is too low, and we will tend to shoot low. To avoid this, we find ourselves placing our cheek very lightly on the comb, or even raising our cheek off the stock a bit. Neither is good for accuracy.
The average American these days can do well with a drop at comb of somewhere in the range of 1.5 to 1.75 inches.
Drop a perpendicular from the line of sight to the heel, as at "C-C", and the measurement is called 'drop at heel'. This is much less important to gun fit than drop at comb. Whereas a small change in drop at comb can make a big difference, a fairly wide range of measurements of drop at heel can be comfortably accommodated by the average shooter. One thing which does change with this measurement is the perceived recoil. A gun with little drop at heel is said to have a "straight" stock. Recoil is more in line with the stock, more directly back into the shoulder, with a straight stock, and more comfortable for most shooters. Stocks with large drop at heel can be painful to shoot, because the comb recoils up against the cheek
Average Americans are comfortable with drop at heel measurements of from 2.25 to 3.0 inches.
The distance "D-D" in the diagram is designated the 'trigger pull'. This is a very important measurement when considering stock fit. It is defined as the distance from the center of the butt to the center of the trigger. It is easily seen that it is also a fairly direct measurement of the length of the buttstock of any gun. Too long a distance here will force the shooter away from the gun, move his cheek back from the point of the comb where it belongs, and cause him to "crawl" the stock in attempting to compensate. The butt will also tend to catch in his clothes as he quickly mounts the gun. Too short a distance is uncomfortable to get lined up, forcing the shooter to ease his face back, away from the breech, in order to line his eye up correctly. A too-short trigger pull will also result in having the thumb smack the shooter in the nose under the recoil of firing.
The average shooter can easily accommodate a range of trigger pulls from 13 to 14 inches. This depends very much on how tall the shooter is, and how long his arms are. Many old guns had trigger pulls as short as 12 inches, but most modern shooters will like one around 13.25 to 13.5 inches.
In the diagram above, there is a solid line from "C" at the heel, across the breech and into the air above the front sight. This is the line of 'pitch'. Pitch is simply defined as the angle of the butt to the line of sight. Give it some thought, and you will see that it is another important consideration of gun fit. Stand your gun on the floor, butt plate flat. Scoot it back until the breech area touches the wall. Measure straight out from the wall to the tip of the muzzle. That measurement is called the "pitch", and is shown as the distance "A-A" in the diagram above. A moment's reflection will show that the measurement depends on two things .... the angle of the butt, and the length of the barrel. The same gun with a 20-inch barrel will have a lot smaller pitch than it would with a 40-barrel. Simple geometry. So, if you ever need to describe a gun in terms of pitch, it is mandatory that you designate the length of the barrel, as in "a pitch of 2.5 inches for a 32 inch barrel". If there was a gap between the muzzle of your gun and the wall when you measured this, then the pitch is said to be 'positive' If the muzzle and the breech both touch the wall, the pitch is 'zero'. If the muzzle touches the wall, but the breech cannot, the pitch is said to be 'negative'. A gun with just the right pitch will stay firmly planted on your shoulder when mounted, and when fired. One with too much pitch will tend to slide up over the shoulder, and will tend to shoot low. One with too little pitch (zero or even negative), will tend to slide down into your armpit, and will tend to shoot high. A little positive pitch makes most of us happy.
It can be confusing to picture, but it's important to keep in mind that pitch has nothing to do with drop. A perfectly straight stock can have a small or a large pitch, and a stock with a radical drop, like some longrifles, can have a zero pitch.
The terms 'cast-off' and 'cast-on' are also used to describe stock configuration. Simply put, they refer to the deviation of the butt away from the center line of the gun. A gun with no cast is straight. A line down the center of the barrel will continue straight down the center of the butt stock, as viewed from above. With cast-off, the center of the butt is moved in the direction of the shoulder of the shooter. The opposite is true of cast-on, the butt deviating toward the center of the shooter's chest. The diagram at left shows cast-off in a right handed gun, by the amount between the arrows. Neither cast-off or cast-on are commonly built into guns, these days, and cast-on has always been fairly rare. The purpose of both is simply to make it easier to align the eye with the sights. Just as the height of the comb helps align the eye with the sights in a vertical direction, up and down, cast can make it easier to line the eye up in a side to side direction. A knowledgeable stock builder can use cast to cure alignment problems for people with particularly wide or narrow faces, for example. This curve in the stock can be accomplished either by steam-bending the straight stock or by carving the curve in as the gun is made, which is better.
Cast-off and cast-on are used far less frequently than most other elements to affect stock fit. The British have always made a big point of the usefulness of cast, especially in shotguns, which must come to the shoulder quickly and without hesitation, lined up right the first time. Few modern American guns have ever had it, and most of the available black powder guns in today's market are made without cast, as far as I am aware.
The average shooter will find a gun with 1/8 to 3/8 inch of cast-off to be a comfortable one to shoot.
Drop at comb, drop at heel, trigger pull, pitch and cast are only a few of the elements which go into making a well-fitting stock, but they are some of the most important to be considered. To these must be added thickness of comb, width, position and angle of the cheekpiece, width of the butt and others. Of course, the size and shape of the shooter must be considered, as well as the shooting sport for which the gun is intended. A shotgun intended for trap, where the target is always climbing away from the shooter, needs to fit the gunner in a different way than that used for skeet or mixed small game, and both will be different from any rifle, whether used for off-hand or bench shooting.
Because of the fact that it is used in an almost automatic, instinctive way, the fit of a shotgun is most critical. The need for proper fit in an off-hand rifle is probably a close second. The fit of rifles used for bench shooting is not as critical, because we can adapt ourselves to any misfits fairly easily, given enough time before we shoot. It's the hand-held guns, especially those used for moving targets, or with no rear sight, to which closest attention to fit should be paid.
The support for a gun can be considered to be 4-point: butt against the shoulder, cheek against the stock, trigger hand at the wrist and the other hand supporting and guiding the barrel. If all these points are comfortably related so that you don't have to do anything radical to get into shooting position ...smashing your face against the stock to get the sights lined up, crawling forward on the stock, lifting your face from the stock, etc.... then painful recoil is not usually a problem, and you can do your best shooting.
A well-fitting gun is a joy to shoot, and can improve your shooting without your ever understanding all the elements involved. Think about a few of the factors discussed here the next time you buy a gun. It will pay dividends in the long run.
Copyright © 1999 B.E. Spencer, all rights reserved.
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