The Colt M16A1 is a usa-made semi-automatic rifle chambered in 5.56x45mm NATO, introduced in 1963. Primary use: Military. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 20 Year introduced: 1963, USA Weight: 86 oz Overall length: 39.5" Status: Discontinued Military use: Yes Intended use: Military