“Projectile force is, therefore, to be increased by resistance; and the knowledge of this fact offers us a practical hint, that when we stand immoveable to our shot, not only by holding the gun tightly to our shoulder, but by also _leaning somewhat forward_ in our shooting attitude, we considerably increase the resistance, and, consequently, we not only lessen the shock of the recoil to ourselves, but we aid the force of the shot and extend its range. That such is the case, may be further exemplified by the following experiment:--Throw a hand-ball against any moveable body, and it will displace that body; but the ball will drop to the ground perpendicularly, however hard the body against which it is thrown may be. Fix the same body securely, and then the rebound of the ball will be nearly equal to the force with which it was thrown.”
The weight or amount of force with which a gun recoils against the shoulder, is due to, and regulated by, several circumstances. The first and most important is the amount of explosive force generated before the charge is moved and during the act of moving, and the amount of inertia in the body of the projectile. When a quantity of gunpowder is exploded without any resisting weight in front of it, then the column of air gives comparatively a slight recoil; though there is, in fact, considerable recoil, but such as is due to the resistance of the air only, and, consequently, more like a push than a blow. The exact amount of recoil is also due to the difference between, or proportionate weights of, the charge of shot or bullet and the gun; action and reaction being always equal until one or the other body moves; the division then will be in favour of that moving fastest, and hence the obtaining of accelerative velocity: it thus follows, as a truism, that the smaller the quantity of exploded gases that can be employed to first move the charge, the less the recoil.
The advantage of the granulation system is here again most clearly shown; and (alluding again to the law of putting matter in motion gradually) if you would gain the greatest benefit, it is clear that, in the same length of tube, you would, at the termination of the accelerative power, have gained a much greater amount of velocity than could be obtained under any other circumstances with the more violently explosive gunpowder.