.30-06 Springfield

The .30-06 Springfield cartridge (pronounced "thirty-aught-six" ˈθɝɾi ɔt sɪks), 7.62×63mm in metric notation, and called the .30 Gov't '06 by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in military use until the late 1970s. The ".30" refers to the caliber of the bullet in inches, .300 and the "06" refers to the year the cartridge was adopted, 1906. It replaced the .30-03, 6mm Lee Navy, and .30-40 Krag cartridges. The .30-06 remained the U.S. Army's primary rifle and machine gun cartridge for nearly 50 years before being replaced by the 7.62×51mm NATO and 5.56×45mm NATO, both of which remain in current U.S. and NATO service. It remains a very popular sporting round, with ammunition produced by all major manufacturers. In the early-1890s, the U.S. military adopted the smokeless powder .30-40 Krag rimmed cartridge. The 1894 version of that cartridge used a round-nose bullet. Around 1901, the U.S. started developing an experimental rimless cartridge for a Mauser action with a box magazine. That led to the 1903 .30-03 rimless service round that used the same round-nose bullet as the Krag. The .30-03 achieved a muzzle velocity of . Many European militaries at the beginning of the 20th century were adopting lighter-weight (roughly ), higher velocity, service rounds with pointed (spitzer) bullets: France in 1898 (8mm Lebel Balle D spitzer with boat-tail), Germany in 1903 (7.92×57mm Mauser S Patrone), Russia in 1908 (7.62×54mmR Lyokhkaya pulya [light bullet]), and Britain in 1910 (.303 British Mark VII ). Consequently, the round-nosed U.S. .30-03 service cartridge was falling behind. For these reasons, the U.S. military developed a new, lighter cartridge in 1906, the .30-06 Springfield, "cartridge, ball, caliber .30, Model of 1906", or just M1906. The .30-03 case was modified to have a slightly shorter neck to fire a spitzer flat-based bullet that had a ballistic coefficient (G1 BC) of approximately 0.405, a muzzle velocity of , and a muzzle energy of .