Many theories have been advanced, and many conjectures made as to the cause of the recoil of guns; and it must be evident that the causes vary with the form of gun, with the nature of the gunpowder, and the weight; or peculiar arrangement of the shot or bullet. For instance, an ounce of shot, and an ounce of lead in the form of a round bullet, fired from the same gun would give two very different amounts of recoil, when measured by the spring cushion; the ounce bullet not giving much more than half the recoil produced by the ounce of shot. This is owing to the simple fact that the bullet being a compact body, offers only the resistance of its weight, and the simple friction of sliding or rolling along the barrel according as it is tight or loose; but the tendency of the hundreds of shot corns is to “jam and wedge” in the most extreme manner, offering, by their lateral pressure against the sides of the barrel, the greatest amount of friction and reluctance to be driven out: hence the reaction on the gun, and thence on the shoulder of the shooter; and the smaller the size of shot the greater the jamming. Again, the same weight of shot, fired from a 16-bore and a 12-bore will recoil much more in the smaller than in the larger bore, even when all other points are equal; because the charge reaches higher in the 16-bore, thus offering at first a greater amount of inertia. Secondly, there is also more tendency to jam; and, thirdly, the extension of the surface of lateral pressure on the tubes of the barrel must also add to recoil. Dirty guns, it is well known, kick violently, simply from the greater friction, or difficulty of the matter of the charge being put in motion.
The question as to what the actual amount of recoil really is has never been settled satisfactorily; the most erroneous opinions have been given, and assertions equally erroneous have been made, by those who have attended to the subject. To clearly elucidate this question, it is absolutely necessary that the circumstances be reduced to one standard: but the difficulty is to obtain that; for it would vary according to muscular development, the weight and height of the sportsman. Indeed any principle laid down would be liable to be disputed, from the very different way in which every sportsman lifts his gun to his shoulder: if one presses it against his shoulder with a pressure equal to 5 lbs., he will receive a certain amount of recoil; he that presses it with a force equal to 10 lbs. will receive less; and with a pressure of 30 lbs. it will be found to yield the least of all. I will illustrate it in this way. Take a spring cushion (something like the spring machine found at all fairs for testing the force of a man pressing against it), if you allow a gun to recoil against this when the starting pressure is only 5 lbs., it will drive it up to 70 lbs., or nearly so, from the velocity with which you have put the 7 lbs. of matter which is contained in the gun into a long sweeping blow. The next time you try, put the starting point at 10 lbs., and you will find a much less result in the extreme weight denoted; but carry on this experiment, placing the cushion with a resisting force of 30 lbs., and you will find the extreme recoil indicated at from 40 lbs. to 45 lbs., and even up to a higher starting resistance. But to this extent it is not advisable to go, for the strain becomes too great on the handle of the gun-stock, and there is too near an apparent approach to a solid resistance, which it is well-known would break the best stock that was ever made.
Having shown how we may approximately obtain the exact amount of force, and how it may, even with two persons, give different results, I will now state what I have found to be the result of many hundreds of trials made with the view of deciding this question. Before doing so, however, I will further premise that hundreds of attempts have been made at various times by different Governments, and by many talented men, to obtain a correct recoil machine which shall efficiently measure the recoil, and in such a perfect line with the intended direction of the projectile as to obtain accurate results: but this is found to be perfectly unattainable, though I believe the nearest approach to it has been made by Mr. Whitworth during his experiments with the hexagonal rifle.
To prove that it is impossible to get all the circumstances alike, so as accurately to ascertain the exact force of the recoil, one instance only need be cited. Fire your gun at a fixed object, then fire at an object in motion, and to your senses the recoil will appear double when fired at the fixed object; but it is not really so: in the latter instance, the body of the person firing the gun, and the gun itself being in motion, a considerable amount of the force of the recoil is absorbed in overcoming the motion of the gun, and then that of the shooters body, so that the effect is not noticed. I have already alluded to the greater force of recoil felt from the lighter pressure of the gun against the shoulder; here the tendency of the gun and body moving in one direction is to close them together, and the proportion will be as the velocity of that movement. Therefore, to bring this to a conclusion, I find that under ordinary circumstances a 12-bore gun of 71⁄2 lbs. weight, 30 inches in length, with a charge of 21⁄2 drams of No. 5 grained gunpowder, and 11⁄4 oz. shot, the barrels draw-bored cylindrically, with the least possible easing at the breech ends, and metal of the best laminated steel, will recoil with a force of from 40 lbs. to 48 lbs., or on an average 44 lbs.: this is the most satisfactory conclusion I have been able to draw from my experiments. This of course will vary, as I have shown; and it is also liable to deviations, according to the state of the atmosphere, and other collateral circumstances. Great variations will of course arise from guns of fine or rough insides; guns new or old, well kept or neglected; and in guns bored larger at the breech-ends, in order to give artificial resistance to the escape of the charge. These last are now, I trust, obsolete, except in that abortion of science the “French breech-loading crutch gun;” and as an exception, all ill-constructed guns.
The science of the question may now be regarded as clearly established. Gun-barrels of the utmost tenacity, with insides of a cylindrical form as true as possible, polished as fine as a mirror, with a moderate weight of shot calculated to suit the gun and a good charge of large granulated gunpowder, will give the greatest killing power, with the greatest amount of comfort, or absence of recoil, that is to be found in the pursuit of shooting.
A point of considerable importance in obtaining regular and good shooting—one, however, which is frequently neglected—is that of ascertaining what sized shot is particularly suited to the size of bore used.
The correct adaptation of No. 5 or No. 6 for your particular gun is easily attained. Place in the muzzle an ordinary wadding, press it into the barrel the depth of the diameter of the shot, which should be exactly flush with the muzzle, place as many shot corns on this as you can, without having more than one distinct layer, and observe the size that best fills, in concentric rings, the whole circumference of the bore, leaving no half-spaces unfilled; note whether it be No. 5 or No. 6 shot, and keep to that size for your general shooting. Again, on other occasions you may wish to use larger shot (Nos. 4, 3, or 2); then ascertain by the same method which fills the concentric rings most perfectly: the same should be done with the smaller sizes, Nos. 8 or 9.
The rationale of this proceeding is that any half-spaces are filled by shot from above pressed in upon the lower layer, disfiguring itself and those it comes into contact with; this is multiplied up to the 13 or 14 layers of which the charge is composed, and the inevitable result is that four or five pellets are pressed together until they adhere; either “balling” or leaving empty spaces in the distribution of the charge, to the injury of the gun’s shooting—a defect which may easily be obviated by attending to the instructions given above. One other point may be observed, viz., that if 11⁄4 give 151⁄2 layers of shot in concentric rings, the charge should be reduced until the rings are complete, for the half-layer will do much mischief by its unequal pressure on the layers beneath it. And it is further necessary to observe that in loading a gun, either with powder or with shot, the gun should be kept as nearly in the upright position as possible: the more upright the gun is held, the more perfectly will it be charged, and the more perfect will be its shooting.
A vast number of useless changes have of late years been introduced into the construction of gunnery; they have died, however, a natural death, as they ought to have done, and have thus afforded additional evidence that sportsmen of the present day only adopt what are really improvements. Great professional reputation in a gunmaker is not now, as formerly, all that is required to command a trial of individual plans of improvement: the improvement must be self-evident; nothing being taken on trust: a bonâ fide benefit to the sportsman is essential in the present day to obtain patronage.
There has lately been introduced a very novel improvement in the construction of double gun barrels, in order to overcome that defect long admitted to exist in firing the second shot. It has long been known that in a 40 yards’ flight, shot falls several inches; and it is an established fact that few sportsmen can kill with the second shot so well as with the first, although it is certainly within range of the gun. This no doubt arises in almost every case, from the shot having fallen below the object in traversing the greater distance; or, in other words, the second barrel, in order to kill as well as the first, ought be fired six inches higher; but this the best shots find it difficult to do, and it has therefore been proposed to do it for them.