The 308 Winchester was introduced to the public as a sporting cartridge by Winchester in September 1952, this same cartridge was accepted by the U.S. military known as the T-65 cartridge in 1954 and began chambering M14 rifles for the round in 1957, this cartridge is also known as the 7.62 NATO cartridge.
Note: Although not identical, the 7.62×51mm NATO cartridge is similar enough to the commercial .308 Winchester that the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) considers it safe to fire the NATO round in weapons chambered for the commercial round.
The 7.62 NATO is a rifle cartridge developed in the 1950s as a standard for small arms among NATO countries. When loaded with a bullet design that tumbles, or fragments in tissue, this cartridge is capable of delivering good terminal wounding performance.
During the 1940s and early 1950s several experiments were carried out to improve on the Garand. One of the most common complaints was the limited capacity en-bloc clip and many experimental designs modified the weapon with a detachable box magazine.
The test program continued for several years, including both the original .30-06 round and a modified .300 Savage (then known as the T65). In the end, the T65 cartridge demonstrated power roughly equal to the original .30-06, firing a 147-grain bullet at 2,750 feet per second but was approximately .5 inches shorter. The eventual result of this competition was the T44 rifle.
When the United States developed the T65 cartridge, the British took a different route. They had spent considerable time and effort developing the intermediate-power .280 British cartridge with an eye towards controllable fully-automatic fire. The T65 was chosen as the NATO standard cartridge in 1954.
The T44 was adopted as the M14 in 1957. The M14s would later go through several variations intended to either limit fully automatic selection through semi-auto version or selector locks or improve control with bipods and/or heavier barrels.
The 7.62x51 cartridge was introduced in U.S. service in the M14 rifle and M60 machine gun in the late 1950s. The M14 and many other firearms that use the 7.62 NATO round remain in service today, especially in the case of sniper rifles and machine guns. The cartridge is used both by infantry and on mounted and crew-served weapons mounted to vehicles, aircraft and ships.