M16A1

The M16 rifle, officially designated Rifle, Caliber 5.56 mm, M16, is the United States military select-fire adaptation of the AR-15 rifle. The rifle was adapted for semi-automatic and full-automatic fire. Colt purchased the rights to the AR-15 from ArmaLite, and currently uses that designation only for semi-automatic versions of the rifle. The M16 fires the 5.56×45mm NATO cartridge. The rifle entered United States Army service and was deployed for jungle warfare operations in South Vietnam in 1963, becoming the U.S. military's standard service rifle of the Vietnam War by 1969, replacing the M14 rifle in that role. The U.S. Army retained the M14 in CONUS, Europe, and South Korea until 1970. In 1983 with the adoption of the M16A2, the M16 rifle was modified for three round bursts, with some later variants having all modes of fire and has been the primary service rifle of the U.S. armed forces.