M16A1

The standard-issue rifle for U.S. Servicemen in Vietnam. Designed by Eugene Stoner as the Ar-15 to replace the M14 (which was difficult to control while in full-auto). The rifle fired .223 caliber ammunition, which later became the 5.56 mm NATO round in widespread use today. The M16A1 "spawned" the current U.S. service rifle, the M16A2, as well as the A3 (full-auto A2), and the M4 Carbine, which is in use by Special Forces units around the world.