The .30-06 Springfield cartridge (pronounced “thirty-aught-six” or "thirty-oh-six") or 7.62 x 63 mm in metric notation, was introduced to the United States Army in 1906 (hence “06”) and standardized, used until the 1960s and early 1970s. It replaced the .30-03, 6 mm Lee Navy and .30 US Army (also called .30-40 Krag). The .30-06 remained the US Army's main cartridge for nearly 50 years before it was finally replaced by the 7.62 x 51 mm (7.62mm NATO, commercial .308 Winchester). It remains the most popular big-game cartridge in North America, and among the most popular worldwide.
Much of the rest of the world at the turn of the century was in the process of adopting the pointed spitzer bullet: France in 1898, Germany in 1905, Russia in 1908, Britain in 1914. When it was introduced, the .30-03 was thus behind the times for this among other reasons. A new case was developed with a slightly shorter case neck to fire a higher velocity, 150-grain (9.7 g) spitzer bullet at 2,700 ft/s (820 m/s).
The M1903 Springfield rifle, introduced alongside the earlier cartridge, was quickly modified to accept the .30-06 cartridge, known as the M1906. Modifications to the rifle included shortening the barrel at its breech and recutting the chamber. This was so that the shorter ogive of the new bullet would not have to jump too far to reach the rifling. Other changes included elimination of the troublesome 'rod bayonet' of the earlier Springfield rifles.
Experience gained in World War I indicated that other nations' machineguns far outclassed American ones in terms of maximum effective range. Additionally, before the widespread employment of light mortars and artillery, long-range machinegun 'barrage' or indirect fires were considered important in U.S. infantry tactics. For these reasons, in 1926, the Ordnance Corps developed the .30 M1 Ball cartridge using a 174-grain (11.3 g) bullet with a 9 degree boat tail, traveling at a reduced muzzle velocity of 2,640 ft/s (800 m/s). This bullet offered significantly greater range from machineguns and rifles alike due to its increased ballistic coefficient. Additionally, a gilding metal jacket was developed that all but eliminated the metal fouling that plagued the earlier cartridge.
Wartime surplus totaled over 2 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 M1 ammunition were allowed to slowly grow until all of the older ammo had been shot up. By 1936 it was discovered that the maximum range of the new M1 ammunition and its 174-grain (11.3 g), boat-tailed bullets was beyond the safety limitations of many ranges. An emergency order was made to manufacture quantities of ammunition that matched the ballistics of the older cartridge as soon as possible. A new cartridge was developed in 1938 that was essentially a duplicate of the old M1906 round, but with a gilding metal jacket and a different lead alloy, resulting in a bullet that weighed 152 grains (9.8 g) instead of 150. This cartridge, the Cartridge .30 M2 Ball, used a flat-based bullet fired at a higher muzzle velocity (2,805 ft/s) than either of its predecessors.
It was used in the bolt-action M1903 Springfield rifle, the bolt-action M1917 Enfield rifle, the semi-automatic M1 Garand, the Browning Automatic Rifle (BAR), and numerous machine guns, including the M1919 series. It served the United States in both World Wars and in the Korean War, its last major use being in Vietnam. Large volumes of surplus brass made it the basis for dozens of commercial and wildcat cartridges, as well as being extensively used for reloading. The .30-06's power, combined with the ready availability of surplus firearms chambered for it, and so demand for commercial ammunition, has made it a popular hunting round. It is suitable for large mammals such as deer, elk, and moose.
The .30-06 is a powerful cartridge designed when 1.0 km (1100 yards) shots were expected. In 1906, the original M1906 .30-06 cartridge consisted of a 9.7 g (150 grain), flat-base cupronickel-jacketed-bullet. After WWI, the U.S. military needed better long-range performance machine guns. Based on weapons performance reports from Europe, a streamlined, 11.2 g (173 grain), boat tail, gilding-metal bullet was used. The .30-06 cartridge, with the 11.2 g bullet was called Cartridge, .30, M1 Ball. The new M1 ammunition proved to be significantly more accurate than the M1906 round.
In 1938, the unstained, 9.8 g (152 grain), flat-base bullet combined with the .30-06 case became the M2 ball cartridge. According to U.S. Army Technical Manual 43-0001-27, M2 Ball specifications required 835 m/s (2,740 feet per second) velocity, measured 24 m (78 ft) from the muzzle. M2 Ball was the standard-issue ammunition for military rifles and machine guns until it was replaced by the 7.62 x 51 mm NATO round for the M14 and M60. For rifle use, M2 Ball ammunition proved to be less accurate than the earlier M1 cartridge; even with match rifles, a target group of 5" (125 mm) diameter at 200 yards (183 m) using the 150-grain (9.7 g) M2 bullet was considered optimal, and many rifles performed less well. The U.S. Marine Corps retained stocks of M1 ammunition for use by snipers and trained marksmen throughout the Solomon Islands campaign in the early years of the war. In an effort to increase accuracy, some snipers resorted to use of the heavier .30-06 M2 armor-piercing round, a practice that would re-emerge during the Korean War. Others sought out lots of M2 ammunition produced by Denver Ordnance, which had proved to be more accurate than those produced by other wartime ammunition plants when used for sniping at long range.
Commercially manufactured rifles chambered in .30-06 are popular for hunting. Current .30-06 factory ammunition varies in bullet weight from 7.1 g to 14.3 g (110 to 220 grains) in solid bullets, and as low as 3.6 g (55 grains) with the use of a sub-caliber bullet in a sabot. Loads are available with reduced velocity and pressure as well as increased velocity and pressure for stronger firearms. The .30-06 remains one of the most popular sporting cartridges in the world.