Windham Weaponry HBC (Heavy Barrel Carbine) with 20-inch heavy profile barrel. A2 stock and fixed carry handle for classic M16 configuration. Type: Semi-Auto Rifle Action: Semi-Automatic Caliber: 5.56x45mm Capacity: 30 Year introduced: 2013, USA Weight: 80 oz Overall length: 39.5" Status: Active Intended use: Service Rifle/General Purpose