The Colt M4A1 is a usa-made semi-automatic carbine chambered in 5.56x45mm NATO, introduced in 1994. Primary use: Military, Tactical. Type: Carbine Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 1994, USA Weight: 86 oz Overall length: 39.5" Status: Active Military use: Yes Intended use: Military, Tactical