If the grooves twist or turn over from left to right, the balls will be carried to the right; and if from right to left, they will group to the left; and this result will be great in proportion to the degree of spirality. The causes of Drift or “Derivation” will be treated of [hereafter]. We know from observation that the majority of balls strike to the right of the mark. The recoil and pulling the trigger throw back the right shoulder, which tend to increase the “derivation” to the right. If the twist were, then, from right to left, the drift, error from pulling, and from recoil, would tend to neutralize each other; the twist of the grooves should therefore be from right to left, instead of the present universal practice of from left to right.
On length of barrel.
The barrel of a gun may be looked upon as a machine in which force is generated for the propulsion of the bullet. It is well known that the continued action of a lesser force, will produce a much greater effect, than a greater amount of power applied suddenly; hence mild gunpowder is more suitable for rifle shooting than strong, or that which evolves the whole of its gas instantaneously. Time is necessary for the entire combustion of a charge of gunpowder, consequently more mild gunpowder can be fired out of a long, than out of a short barrel, as if fired out of a short barrel, some of the grains might be ejected unconsumed. All extra length, after the last volume of gas is evolved, can only be injurious, by causing loss of velocity from friction. A billiard ball would travel none the further nor straighter, were it to be propelled through a hollow tube, neither would a barrel to a cross bow aid in killing rooks. Favors expansion.A barrel favours expansion of the bullet, which is produced by the force of the generated gas, opposed by the column of air in the hollow tube and by the motion of the projectile. Assists aiming, firing two deep: when using bayonet.Facility in aiming is promoted by the sights being distant from each other. In a military arm a certain length is necessary in order to fire when two deep in the ranks, and length is also advantageous, should the rifle be used as a pike.
Advantages of short rifle.
The short rifle can be held steadier when standing, by a weak man, and during wind, it is handy when passing through a wood or thicket, and a very short man has more command of his gun when loading; Disadvantages of short rifles.but with the sword bayonet, it is heavier than the long Enfield and bayonet; while the sword is very inconvenient when running, firing kneeling, or lying down.
Thickness of barrel.
Great substance was at one time considered necessary for accurate firing, it being supposed necessary to prevent vibrations in the barrel; this is true within certain limits, and the heavier the charge, the heavier the metal ought to be, especially at the breech, but diminishing the thickness, has been proved in no wise to lessen the accuracy. A heavy barrel also lessens recoil, but it would be folly to carry more weight than would neutralize the recoil which could be produced by a greater charge of powder than could be consumed in a given length of barrel.
Size of bore.
The two grand requirements of a soldier’s gun are, celerity of loading, combined with accuracy at long ranges; and the distance at which he should have the power of firing, should be limited by the strength of his eye. The weight of the projectile being fixed (·530 grs.), good shooting at extreme distances can only be obtained by reducing the diameter of the bore, which, lessening the frontage of the bullet, causes it to experience less resistance from the air; it therefore retains a higher degree of velocity than a larger bullet of the same form and weight, and therefore travels further and faster. Gravity has less time to act upon it, in a given distance, and therefore it can be fired at a lower angle, or has what we call a lower trajectory, and its accuracy is increased in direct proportion to the lowness of its flight, all other things being equal.
Best form of rifling still undetermined.