The devices used foe' securing rifling have undergone various changes during recent years, as the muzzle-loading methods have been forced to give way to the more modern breech loaders. Studded projectiles having buttons or flanges, which followed the grooves in the gun, were very popular abroad, whereas in this country we preferred expanding rings at the base of the projectile. These rings carried an annular groove in which the powder gases acted in such a manner that they forced the outer portion of the ring into the rifling grooves, and, at the same time, caused the ring itself to more closely grasp the shell. In breech load ing guns there is a band of soft metal about the projectile which makes it a little larger in diameter than the caliber of the gun ; the powder gases force this band to take the grooves, and, by this means, the twist is imparted to the projectile.
Projectiles against is worthy of note that with the improvement of the steel projectile, the steel face of compound armor became more and more hardened, and carbon was added until there was 40 per cent, more used in 1888 than had formerly been thought necessary. When the Holtzer projectiles were tried in England, in March, 1887, the excellent results obtained were claimed to be largely due to the fact that the plate was of inferior quality, and a new trial came off in October of the same year, the target being the best 16-in.
compound plate that could be made. It was in fact the second half of the plate that had so successfully withstood the attacks of Firminy projectiles in the early part of the year. The projectile weighed 714 lbs.; the plate was broken into two parts, and cracks were devel oped all over its surface. When removed from the target-backing the shell was intact, and so little deformed that, apparently, it could have been fired again. A Palliser shot fired under similar conditions to a Holtzer was shattered into fragments.
A lot of 300 Holtzer 6-in. shell were fired at Shoeburvness against a Brown 9-in, compound plate. The first shell perforated the plate without further injury than a slight cracking in the head; the second failed to get through, and, breaking off at the front band, rebounded 12 yards. As the requirements were that test shell should pass through a 9-in. compound plate practically undeformed, the lot was rejected. A former lot had, however, passed the test, as did some Holtzer steel projectiles fired against Creusot plates 5.5 in. thick.
Early in 1888, projectiles 13.5 in. in caliber, weighing 1,250 lbs., were fired against
Cam tnell plates 18 in. thick. The first shot against this plate was a Firminy shell and was completely broken up. A St. Chamond projectile was fired against a Brown plate during the same series of trials, and was also broken up. Firing against a Brown 9-in. plate was tried later in the same year, Firminy 6-in. shells being used. The two test shells passed through the plate and were but slightly cracked and deformed. An armor-piercing trial with St. Chatnond 12-in. projectiles took place in Russia; the plate was of the Wilson patent, but made in Russia. Although the plate was fractured, the shot did not get through; the point barely pierced the plate, leaving the base projecting from the other side, the surface of the projectile being badly cracked in all directions.
In 1890 there were two important trials of projectiles versus armor: the first in this country at Annapolis, and the second at Ochta, in Russia. At the former the energy of the 6-in.
Holtzer armor-piercing projectile was a little more than sufficient to just perforate the steel plate. The other two plates used were a nickel-steel and a compound armor. There were twelve 6-in. 100-lb. projectiles fired, four at each plate. with the following results : The first shot fired at the steel plate was not materially injured, its base projected 6.5 in. from the plate; the second penetrated but rebounded, and was found to be shortened 10 of an inch; the third did the same, and was shortened .14 of an inch ; the fourth acted in the same manner, but was broken up. The compound plate let the first three through without injury to the projectiles, but the fourth broke after perforation. The body of the first shell fired at the nickel-steel remained in, but the rear end rebounded; the second remained intact in the plate ; the third the same, excepting that the base projected 4.5 in.; while the fourth broke, leaving its head in the plate, the rear portion rebounded. A fifth shot was fired at each plate, the projectile being an 8-in. Firth-Firminy. The one fired at the steel plate penetrated, rebounded, and broke in three pieces. The nickel-steel let the projectile enter, but broke it 5.25 in. from the face of the plate, part of the head remaining in the hole. The shell fired at the compound plate was recovered entire, but was shortened 0.24 in.; much of the plate was damaged, the hardened front portion was scaled off in a number of large and small pieces.