The Colt 6721 is a commercial-channel variant of the Colt 6720 mid-length series, featuring a 16-inch mid-length gas system barrel with M4-profile chrome-lined bore and a flat-top upper receiver. The 6721 designation appears in Colt's internal commercial product line documentation and is distinguished from the LE6920 by its mid-length gas system and distribution channel. Factory Colt with mil-spec components throughout. Type: Rifle Action: Semi-Automatic Caliber: 5.56 NATO Capacity: 30 Year introduced: 2012, USA Weight: 6.36 oz Overall length: 32.5" Status: Discontinued Intended use: Sport Shooting, Tactical