[Footnote 2: Hunters still dispute as to iron or steel; and we have used iron barrels made by Amsden, of Saratoga Springs, which for accuracy and wear were unexceptionable; though gunsmiths generally take less pains with iron than steel barrels. But give us steel.]
Of all the variations of the rifle, for the sake of obtaining force of penetration, nothing yet compares with the Accelerating Rifle, invented some years since by a New York mechanic. In this the ball was started by an ordinary charge, and at a certain distance down the barrel received a new charge, by a side chamber, which produced an almost incredible effect. An ellipsoidal missile of ninety gauge and several diameters long, made of brass, was driven through thirty-six inches of oak and twenty-four inches of green spruce timber, or fifty inches of the most impenetrable of timbers. The same principle of acceleration has, it is said, been most successfully applied in Boston by the use of a hollow tige or tube fixed at the bottom of the bore with the inside of which the cap-fire communicates,—so that, when the gun is charged, part of the powder falls into the tige, and the remainder into the barrel outside of it. The ball being driven down until it rests on the top of the tige, receives its first impulse from the small charge contained in it,—after which, the fire, flashing back, communicates to the powder outside the tige, producing an enormous accelerating effect. But it is doubtful if the gun can be brought into actual service, from being so difficult to clean.
It is questionable if any greater range in rifles will be found desirable. With a good Kentucky rifle, we are even now obliged to use telescope sights to avail ourselves of its full range and accuracy of fire. The accelerating inventions may be made use of in artillery, for throwing shells, and for siege trains, but promise nothing for small arms.
Then, as the secondary point, comes the form of projectile, that in which the greatest weight (and thence momentum) combines with least resistance from the atmosphere. In the pursuit of this result every experimenter since the fifteenth century has worked. Lautmann, writing in 1729, recommends an elliptical missile, hollow behind, from a notion that the hollow gathered the explosive force, Robins recommends elongated balls; and they were used in many varieties of form. Theory would assign, as the shape of highest rapidity, one like that which would be made by the revolution of the waterline section of a fast ship on its longitudinal axis; and supposing the force to have been applied, this would doubtless be capable of the greatest speed; but the rifle-missile must first be fitted to receive the action of the powder in the most effective way. An ellipsoid cone would leave the air behind it most smoothly, but it would not receive the pressure of the gas in a line with its direction of motion; and so of the hollow butt; the gas, acting and reacting in every way perpendicularly to the surface it acts on, wastes its force in straining outwardly. The perfectly flat butt would take as much forward impetus at the edge of the cone base, where the soft lead would yield slightly. And so we find the best form to be a base which receives the force of the powder in such a way that the resultant of the forces acting on each point in the base would be coincident with the axis of the missile. And this, in practice, was the shape which the American experiments gave to the butt of the ball, the condition in which it left the air being found of minor importance, compared with its capacity of receiving the force of the powder. The point of the cone was found objectionable in practice, and was gradually brought to the curve of the now universally used sugar-loaf missile or flat-ended picket shown in fig. 1.
[Illustration: Figure 1]
This picket has but a single point of bearing, and is driven down with a greased linen patch, filling up the grooves entirely, and preventing "leading" of the barrel, as well as keeping the picket firm in the barrel. This is of vital importance; for no breech-loading or loose-loading and expanding ball can ever fly so truly as a solid ball whose position in the barrel is accurately fixed. A longitudinal missile must rotate with its axis coincident with its line of flight as it leaves the barrel, or else every rotation will throw the point into wider circles, until finally it becomes more eccentric than a round ball. It is a mistaken notion that a conical missile is more accurate in flight than a round; on the contrary, hunters always prefer the ball for short shots,—and a "slug," as the longer missile is called by them, is well known to err more than a ball, if put down untruly.
[Illustration: Figure 2]
The improved Minié ball (fig. 2) was intended to obviate the danger of the missile's turning in flight, by hollowing the butt, and so putting the centre of gravity in front of the centre of resistance, so that it flies like a heavy-headed arrow, while at the same time the powder expands the hollow butt and fills the grooves, securing perfect rotation with easy loading. But the hollow in the ball diminishes the gravity and momentum; the liability of the lead to expand unequally, and so throw the point of the missile out of line, makes a long bearing necessary, producing enormous friction. This objection obtains equally with all pickets having expanding butts, and is a sufficient reason for their inferior accuracy to that of solid pickets fitted to the grooves at the muzzle with a patch. General Jacob says,—"I have tried every expedient I could think of as a substitute for the greased patch for rifle-balls, but had always to return to this"; and every experienced rifleman will agree with him. Yet both English and American (governmental) experiments ignore the fact, that the expansible bullets increase friction enormously; and the Enfield bullet (fig. 3) is as badly contrived as possible, being round-pointed, expansible, and with very long bearings, without the bands which in the French and American bullets reduce the friction somewhat. The Harper's Ferry bullet (fig. 4) is better than either the English or the French, and is as good as a loose-loading bullet can be.
[Illustration: Figure 3]
[Illustration: Fig 4]