The M14 rifle is an automatic rifle used by the United States Armed Forces. It was introduced after the Korean War, in 1957, and saw limited use early in the War in Vietnam. It was replaced by the lighter M16. The M14 used NATO standard 7.62 millimetre bullets, while its replacement the M16 used smaller and less powerful 5.56 millimetre bullets. Ironically, it had been the US that pushed NATO to choose the larger standard bullet.