The Bushmaster Carbon-15 Type 21 is the standard rifle configuration of the carbon-fiber composite AR-15, featuring a 16-inch barrel and the lightweight composite upper and lower receivers that define the Carbon-15 line. Type 21 indicates the full-size carbine versus the Type 97S pistol variant. Weighs approximately 3.9 pounds empty — among the lightest AR-15 production rifles ever built. Type: Rifle Action: Semi-Automatic Caliber: 5.56 NATO Capacity: 30 Year introduced: 2001, USA Weight: 3.9 oz Overall length: 32" Status: Discontinued Intended use: Sport Shooting, Hunting