7.62 x 51 mm (.308 caliber)

The 7.62×51mm NATO (official NATO nomenclature 7.62 NATO) is a rimless bottlenecked rifle cartridge developed in the 1950s as a standard for small arms among NATO countries. It is sometimes confused with the similarly named Russian 7.62×54mmR cartridge, a slightly longer, rimmed cartridge.. It was introduced in U.S. service in the M14 rifle and M60 machine gun in the late 1950s.