The .30-06 Springfield cartridge (pronounced "thirty-aught-six" /ˈθɜːrti ɔːt 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. In the cartridge's name, ".30" refers to the nominal caliber of the bullet in inches; "06" refers to the year the cartridge was adopted, 1906. It replaced the .30-03 Springfield, 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 in 1957 by the 7.62×51mm NATO and 5.56×45mm NATO, both of which remain in current U.S. and NATO service. The cartridge 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 220-grain (14 g) 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 Springfield rimless service round that used the same 220-grain (14 g) round-nose bullet as the Krag. The .30-03 achieved a muzzle velocity of 2,300 ft/s (700 m/s).^{[citation needed]}

Many European militaries at the beginning of the 20th century were adopting lighter-weight (roughly 150-to-200-grain (9.7 to 13.0 g)), higher velocity, service rounds with pointed (spitzer) bullets: France in 1898 (8×50mmR Lebel Balle D spitzer 198 grains (12.8 g) with boat-tail), Germany in 1903 (7.92×57mm Mauser 153 grains (9.9 g) S Patrone), Russia in 1908 (7.62×54mmR Lyokhkaya pulya [light bullet]), and Britain in 1910 (.303 British Mark VII 174 grains (11.3 g)). 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 150-grain (9.72 g) bullet that had a ballistic coefficient (G1 BC) of approximately 0.405, a muzzle velocity of 2,700 ft/s (820 m/s), and a muzzle energy of 2,429 ft⋅lbf (3,293 J). The cartridge was loaded with military rifle (MR) 21 propellant, and its maximum range was claimed (falsely) to be 4,700 yd (4,300 m). The M1903 Springfield rifle, which had been introduced alongside the .30-03 cartridge, was modified to accept the new .30-06 Springfield cartridge. Modifications to the rifle included shortening the barrel at its breech and resizing the chamber, so that the more tapered bullet would not have to jump too far to reach the rifling. Other changes to the rifle included the elimination of the troublesome "rod bayonet" of the earlier Springfield rifles.^{[citation needed]}

The M1906 maximum range was originally overstated. When the M1906 cartridge was developed, the range tests had been done to only 1,800 yards (1,650 m); distances beyond that were estimated, but the estimate for extreme range was incorrect by almost 40 percent. The range discrepancy became evident during World War I. Before the widespread employment of light mortars and artillery, long-range machine gun "barrage" or indirect fires were considered important in U.S. infantry tactics. When the U.S. entered World War I, it did not have many machine guns, so it acquired British and French machine guns. When those weapons were later replaced with U.S. machine guns firing the M1906 round, the effective range of the barrage was 50 percent less. Firing tests performed around 1918 at Borden Brook Reservoir (Massachusetts), Miami, and Daytona Beach showed the actual maximum range of the M1906 cartridge to be 3,300 to 3,400 yards (3,020 to 3,110 m). Germany, which was using the S Patrone (S ball cartridge) loaded with a similar 153-grain (9.9 g) flat-based bullet in its rifles, had apparently confronted and solved the same problem by developing an aerodynamically more refined bullet for long-range machine gun use. The s.S. Patrone was introduced in 1914 and used a 197.5-grain (12.80 g) s.S. – schweres Spitzgeschoß (heavy spitzer) boat-tail bullet which had a maximum range of approximately 5,000 m (5,468 yd).

For these reasons, in 1926, the ordnance corps, after extensive testing of 7.5×55mm Swiss GP11 projectiles provided by the Swiss, developed the .30 M1 ball cartridge loaded with a new improved military rifle (IMR) 1185 propellant and 174-grain (11.28 g) bullet with a 9° boat-tail and an ogive of 7 calibers nose cone that had a higher ballistic coefficient of roughly 0.494 (G1 BC), that achieved a muzzle velocity of 2,647 ft/s (807 m/s) and muzzle energy of 2,675 ft⋅lbf (3,627 J). This bullet further reduced air resistance in flight, resulting in less rapid downrange deceleration, less lateral drift caused by crosswinds, and significantly greater supersonic and maximum effective range from machine guns and rifles alike. Additionally, a gilding metal jacket was developed that all but eliminated the metal fouling that plagued the earlier M1906 cartridge. The loaded round weighed 420 grains (27 g) and its maximum range was approximately 5,500 yd (5,030 m). The maximum average pressure (MAP) was 48,000 psi (330.95 MPa). The average target radius was specified to be not greater than 4.5 in (11 cm) at 500 yd (457 m) and not greater than 5.5 in (14 cm) at 600 yd (549 m) when fired from a Mann accuracy weapon.

Wartime surplus totaled over two billion rounds of ammunition. Army regulations called for training use of the oldest ammunition first. As a result, the older .30-06 ammunition was expended for training; stocks of .30 M1 ball ammunition were allowed to slowly grow until all of the older M1906 ammunition had been fired. By 1936, it was discovered that the maximum range of the .30 M1 ball ammunition with its boat-tailed spitzer bullets was beyond the safety limitations of many military firing ranges. An emergency order was made to manufacture quantities of ammunition that matched the external ballistics of the earlier M1906 cartridge as soon as possible. A new cartridge was developed in 1938 that was essentially a duplicate of the old M1906 round, but loaded with IMR 4895 propellant and a new flat-based bullet that had a gilding metal jacket and a different lead alloy, and weighed 152 grains (9.85 g) instead of 150 grains (9.72 g). This 1938 pattern cartridge, the cartridge, caliber .30, ball, M2, achieved a muzzle velocity of 2,805 ft/s (855 m/s) and muzzle energy of 2,656 ft⋅lbf (3,601 J). The loaded round weighed 416 grains (27.0 g) and its maximum range was approximately 3,450 yd (3,150 m). The MAP was 50,000 psi (344.74 MPa) by copper crusher (equivalent to the SAAMI CUP unit). The average target radius was specified to be not greater than 6.5 in (16.5 cm) at 500 yd (457 m) and not greater than 7.5 in (19.1 cm) at 600 yd (549 m).

In military service, the .30-06 was used in the bolt-action M1903 Springfield rifle, the bolt-action M1917 Enfield rifle, the semi-automatic M1 Garand rifle, the semi-automatic M1941 Johnson rifle, the Famage Mauser, the Browning automatic rifle (BAR), and numerous machine guns, including the M1917 and M1919 series. It served the United States in both World Wars and in the Korean War, and its last major use was during the Vietnam War.^{[citation needed]}