A 12-in, breech-loading rifle, made of east-iron, was built, and tried at Sandy Hook, N. J., in 1886. The gun had the exterior curved outline of the Rodman model, with the thickness of the wall decreasing toward the muzzle, and proportioned to the powder pressure to be withstood in the different sections of the bore. Except the sleeve that holds the breech dock and the breech mechanism, the gun was wholly of east-iron, and in one piece. The erosion of the bore during the trials became so great that gauging was very difficult, flared openings having a depth of 015 of an inch being made.
The first experimental rifled mortar, 12-in. muzzle-loading, was completed in 1884. The reasons leading to the adoption of the muzzleloader for the first experimental type were because it was then thought that the old method of loading from the muzzle would be, on the whole, better adapted to such short pieces, as combining simplicity and cheapness, together with less care and attention required in service, as compared with the breechloader. The piece has been fired over 400 times, and is considered amply strong for service. Its best record for accuracy is a target of ten shots; range, 3,490 yards: 26 lbs. of powder, 610-1b. projectile ; percentage, 99 hits for 100 shots on the deck of a vessel 330 ft. long, and 60 ft. wide.
12-in. breech-loading rifled mortars were, however, thought to be more desirable, as further experiment developed an unsatisfactory degree of accuracy, and a lack of uniform steadi ness in the flight of the shell. In general design these mortars show a short rifled piece of about, nine calibers length of bore, weighing about 14 tons, having the slotted screw-block and breech mechanism, and embodying a new and special design of retracting gear. The body is cast-iron, having two rows of steel hoops shrunk on, extending from the breech over about two-thirds the length of the piece. The trunnions are forged as wirt of one of the steel hoops.
The Navy Department has in hand a 0,in, steel tube wire-wrapped gun, partly completed, The army is wrapping a 10-in. breech-loading cast-iron rifle. The muzzle half of the cast iron body is not covered. A steel trunnion band is shrunk on the outside of the wire, and the portion of wire in front of the band is covered by a steel sleeve, also shrunk on, which will transmit the thrust of the trunnion band to another steel hoop shrunk on the east-iron body, and backed up by a key ring shrunk on cold. The 10-in. carries longitudinal bars,
and is wound from breech to muzzle. The tithe is of steel, and extends entirely through the gun. The longitudinal bars or staves form a cylinder, fitting the tube over about one half its length from the breech, and connected indirectly with the trunnion band and the breech block.
Two steel cast 6 in. guns were built, one of Bessemer steel, and the other of open-hearth steel. The former burst at the second round, and the latter had it permanent extension of the bore, and other defects were developed that caused the rejection of the gun. The steel breech-loading guns are as follows : Quick-five Guns.—The Hotchkiss revolving cannon and the torpedo boat came into prominence about the same time, and for a while the gun was the more powerful, but as the boats were gradually perfected, heavier guns were demanded, and the 1-pounder grew to a 2-pounder and then to a 4-pounder. These guns were found too heavy for their energy and killing power, and the French government suggested a single-barreled gun that was to use metallic ammunition. Mr. Hotchkiss undertook the contract, altered his breech-block so that it would slide vertically, used a very long barrel, and introduced in a 3-pounder the first gun, of its type. England, in 1881, demanded a 6-pounder, and Hotchkiss and Nordenfeldt produced guns that to-day form part of the armament of nearly every great naval power, Germany being the most important exception. In 1883 the United States gave an order for rapid-fire guns which was the first regular order given by any government.
The Hotchkiss is the wedge system of mechanism, and has a falling or vertically moving block, which is as applicable to the 5 and 6-in. calibers as to the 3-pounders, the same design being used of rall, every part being exactly the same pattern, larger or smaller as the caliber requires. The breech-block is worked by a lever arm which travels in a slot, so that the first movement of opening gives but a small descent to the block. This motion becomes quicker, until the block falls freely and throws its full weight in aid of the extraction. The extractors have a straight, positive motion with a long travel, and are actuated by a groove in the breech-block, having a slow motion at first, but exerting powerful leverage as the block is opened wider. The block is supported when open by the head of a stop screw passing through the side of the breech.