"The M1 was first manufactured in 1926 and was used by U.S forces in the Second World War, Korea and during the Vietnam War. The model was only replaced by the M16 in the 1980s.
I thought that was the 60's? Or am I mistaken? "
The M1 Garand was adopted for service by the U.S. Army in 1936, but production was slow. Most units of the U.S. Armed Forces were still armed with the 1903 Springfield at the start of the U.S. involvement in the war on December 7, 1941. It wasn't until production was pumped up at the Springfield Armory, and then Winchester, that the rifles started to get to the troops. My father was at Pearl Harbor when it was attacked by the Japanese, and shot at the straffing Japanese planes with his '03. When he went to Guadalcanal in October of 1942, he was still armed with the same '03, as were the rest of the Marines there. They first saw M1's when they were relieved by the Army, but the Marines retained their '03's for about another year.
The Garand was replaced by the M14 rifle in 1956. When I went into the Marine Corps in 1965, I was issued an M14, and carried it for the next 6 years. The M16 was issued to troops embarking for Vietnam around 1968 or so, but a lot of the stateside troops in the Marine Corps were still issued M14's.
The M16, and it's variants has been the issue rifle since then.
Hope this helps.
Fred