It must be borne in mind that a variation in the length of burst at any particular range may alter the frontage covered considerably, but it hardly affects at all the depth covered by effective bullets. This depth may be taken as 500 yards for ranges of about 1500 yards, 400 yards for ranges of about 2500 yards, and 300 yards for ranges of about 3300 yards, irrespective of the length of short burst.
PERCUSSION-SHRAPNEL.
With shrapnel of this kind the cone of dispersion has an ascending angle which will be much greater than the angle of descent, and would vary with the conditions of the ground struck. The velocity is very much impaired by the retardation on graze, and the smallest irregularity may cause the projectile to bury itself, or rise at a very considerable angle.
The effect being so greatly inferior to time-shrapnel, they would only be used on particular occasions.
CANISTER.
Canister is a collection of bullets contained in a can, which is ruptured in a gun by the shock of discharge, the bullets thereby forming a cone of dispersion with its apex at the muzzle of the gun. The can, or envelope, in the U. S. service is known as the Sawyer, and is made of malleable cast iron, weakened by spiral cuts.
Canister is essentially a close-quarter projectile for employment against personnel and horses, and under the most favorable circumstances is effective up to nearly 500 yards; up to 300 it is annihilating.
Effective ricochets are necessary for maximum results, and can only be obtained at short ranges, and then only over smooth water, or on a hard level surface not intersected with obstacles.