The.30-40 Krag was a cartridge developed in the early 1890s to provide the U.S. armed forces with a smokeless powder cartridge suited for use with modern small-bore repeating rifles to be selected in the 1892 small arm trials. Since the cartridge it was replacing was the.45-70 Government, the round was considered small-bore at the time. The design selected was ultimately the Krag–Jørgensen, formally adopted as the M1892 Springfield. It was also used in M1893 and later Gatling guns.
The .30-4Though the U.S. Navy and Marine Corps had adopted limited numbers of smokeless powder and bolt-action rifles, the .30-40 was the first cartridge adopted by the US Army that was designed from the outset for smokeless powder. After a brief experiment with a 230-grain bullet loading, the .30 Army loading was standardized in 1894 using a 220-grain (14 g) metal-jacketed round-nose bullet with 40 gr (2.6 g) of nitrocellulose powder. This loading developed a maximum velocity of 2,000 ft/s (610 m/s) in the 30-inch (760 mm) barrel of the Krag rifle, and 1,960 ft/s (600 m/s) in the 22-inch (560 mm) barrel of the Krag carbine.0 Krag (also called .30 U.S., or .30 Army) was a cartridge developed in the early 1890s to provide the U.S. armed forces with a smokeless powder cartridge suited for use in rifle and gatling gun.