The M4 Carbine is the compact variant of the M16A2, adopted by the US military as the standard infantry weapon for most personnel, replacing the M16A2 in front-line service. A collapsible stock and 14.5-inch barrel provide more maneuverability in vehicles and buildings while retaining the essential M16 operating system. Type: Carbine Action: Semi-Automatic/Full-Auto Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 1994, USA Weight: 6.43 oz Overall length: 33" Status: Active Military use: Yes Intended use: Military