<P> In the end the United States Army chose the T44 now called the M14 rifle which was an improved M1 Garand with a 20 - round magazine and automatic fire capability . The U.S. also adopted the M60 general purpose machine gun (GPMG). Its NATO partners adopted the FN FAL and HK G3 rifles, as well as the FN MAG and Rheinmetall MG3 GPMGs . </P> <P> The first confrontations between the AK - 47 and the M14 came in the early part of the Vietnam War . Battlefield reports indicated that the M14 was uncontrollable in full - auto and that soldiers could not carry enough ammo to maintain fire superiority over the AK - 47 . And, while the M2 Carbine offered a high rate of fire, it was under - powered and ultimately outclassed by the AK - 47 . A replacement was needed: A medium between the traditional preference for high - powered rifles such as the M14, and the lightweight firepower of the M2 Carbine . </P> <P> As a result, the Army was forced to reconsider a 1957 request by General Willard G. Wyman, commander of the U.S. Continental Army Command (CONARC) to develop a . 223 caliber (5.56 mm) select - fire rifle weighing 6 lb (2.7 kg) when loaded with a 20 - round magazine . The 5.56 mm round had to penetrate a standard U.S. M1 helmet at 500 yards (460 meters) and retain a velocity in excess of the speed of sound, while matching or exceeding the wounding ability of the . 30 Carbine cartridge . This request ultimately resulted in the development of a scaled - down version of the ArmaLite AR - 10, called ArmaLite AR - 15 rifle . </P> <P> In 1958, ArmaLite submitted ten AR - 15 and one hundred 25 - round magazines for CONARC testing . The tests found that a 5 - to 7 - man team armed with AR - 15s has the same firepower as 11 - man team armed with M14s . That soldiers armed with AR - 15s could carry three times more ammunition as those armed with M14s (649 rounds vs 220 rounds). And, that the AR - 15 was three times more reliable than the M14 rifle . However, General Maxwell Taylor, then Army Chief of Staff, "vetoed" the AR - 15 in favor of the M14 . In 1959, ArmaLite now frustrated with the lack of results and suffering ongoing financial difficulties, sold its rights to the AR - 10 and AR - 15 to Colt . </P>

When was the ar 15 used in the military