With the adoption of the M1903 rifle, a new cartridge was also adopted. The cartridge designed for the rifle featured a rimless bottlenecked case, and a round nosed 220 grain bullet, advertised at 2,300 feet per second muzzle velocity.
In 1906, the United States adopted a lighter spitzer bullet of 150 grains and a muzzle velocity of 2,700 feet per second. The maximum range for the new cartridge, now designated the M1906, was found to be between 3,300 and 3,400 yards, with the muzzle of the rifle at an angle between 29 and 45 degrees.
In 1917, the United States declared war on Germany and entered World War One. At the outset of the war, the United States had virtually no machine guns, so troops in France were armed with British Vickers guns, and with French Hotchkiss guns. The Vickers gun fired the .303 Mk. VII round, a 174 grain flat based bullet, and the Hotchkiss used the 198 grain Balle D spitzer boat tailed bullet. It didn't take long for the US machine gun crews to realize that these rounds had extreme ranges nearly fifty percent greater than the M1906. When the US troops were finally issued American Browning machine guns, they were appalled to learn that they could no longer lay machine gun barrages at the same long range as before.
This failing of the M1906 cartridge led to a search for a new service bullet in the period immediately following the war. During the development process, the US Army Ordnance personnel tested the contemporary Swiss service bullet used in the Swiss Army's Schmidt-Rubin M1911 and M1896/11 rifles. This bullet was a 174 grain boat tailed design of the same diameter of the M1906 loading, that is .308 inch. The tests revealed that the Swiss bullet was immensely superior to the M1906 with respect to long range performance.
As a result of the tests, a 174 grain bullet with a 9 degree boat tail taper and an ogive of 7 calibers in radius was adopted as the .30 caliber M1 in 1925. Muzzle velocity of rounds loaded with the M1 bullet was 2,640 feet per second, giving an extreme range of 5,500 yards.
In 1925, when the new M1 round was standardized, there were two billion .30-06 rounds in store. The Army's policy at the time was to use the oldest ammunition first, keeping the newest supply for war reserve. These two billion rounds were finally expended in 1936, and only then was the M1 ammunition issued in bulk for training. Upon the issuance of the M1 ammunition, there was an alarming realization - the M1 ammunition had so much more range and momentum than the M1906 ammunition that it began to shoot beyond the impact zones of existing ranges! The National Guard Bureau (NGB) then asked the War Department to make up a batch of ten million rounds with the same characteristics as the old M1906 round.
The "new" short range ammunition was virtually a clone of the M1906 round. It used a 150 grain flat based bullet, but the ogive was shaped like that of the M1. By the late 1930's, this "new" ammunition had reached the service evaluation boards (by now minus all the old World War One machine gunners who had so keenly felt the lack of range in the original M1906 round). The new round had lower recoil than the M1, and more rounds could be carried for a given weight of ammunition, so in 1940, the new round (with a bullet weight of 152 grains owing to a slightly different lead alloy) was standardized as the Cartridge, Ball, Caliber .30, M2. The M2 cartridge boasted a muzzle velocity of 2,805 feet per second. The armor piercing analog to the M2, the Cartridge, Armor Piercing, Caliber .30, M2 fires a 168 grain bullet at 2,775 feet per second muzzle velocity.
The story did not end there, however. The 1936 - 1940 period, when the M2 cartridge was being standardized was the same time frame that the M1 Garand rifle was coming into service. The change in service ammunition led to unfounded and false accusations that the new rifle couldn't handle the M1 ammunition. This was, of course, totally false, the reasons for the change having to do with size of the then existing training ranges...
