The Bushmaster Carbon 15 in .300 Blackout was a lightweight polymer-receiver AR-15 that chambered the then-new .300 BLK cartridge. The carbon fiber-reinforced polymer construction reduced weight to under 5 pounds unloaded, making it unique among early .300 BLK production rifles. Type: Rifle Action: Semi-Automatic Caliber: .300 Blackout Capacity: 30 Year introduced: 2011, USA Weight: 48 oz Overall length: 32.5" Status: Discontinued Intended use: Home Defense, Hunting, Lightweight