Ammunition
The U.S. Krags were chambered for the rimmed .30-40 Krag round, also known as ".30 Army." From 1890 to 1893 a 230-grain steel or cupro-nickel jacketed bullet was issued, for which no ballistic data is known. From 1894 to September 1899 a 220-grain jacketed bullet loading was issued using 40 grains of nitrocelluose powder, which developed some 40,000 psi and a muzzle velocity of 2,000 feet per second (610 m/s) in the Krag rifle and 1,960 ft/s (600 m/s) in the shorter carbine. In October 1899, after reviewing the experiences of the Spanish-American War, a new loading was developed for the .30 Army in an attempt to match the ballistics of the 7x57mm Mauser cartridge. The new loading increased the Krag rifle's muzzle velocity to 2,200 f/s at 45,000 psi. However, once the new loading was issued, reports of cracked locking lugs on service Krags began to surface. In March 1900 the remaining stocks of this ammunition, some 3.5 million rounds, was returned to the arsenals, broken down, and reloaded back to the original 2,000 ft/s (610 m/s) specification.
Although the .30-40 Krag was the first smokeless powder round adopted by the U.S. military, it retained the "caliber-charge" designation of earlier black powder cartridges, thus the .30-40 Krag employs a .30 caliber (7.62 mm) bullet propelled by 40 grains (3 g) of smokeless powder. As with the .30-30 Winchester, the use of black powder nomenclature led to the incorrect assumption that the .30-40 Krag was once a black powder cartridge.
Read more about this topic: Springfield Model 1892-99