Diamondback 300 AAC Blackout 16in Black Nitride Semi Automatic Modern Sporting Rifle - 30+1 Rounds - This Diamondback DB15 Rifle features a pistol-length, heavy 4150 chrome moly barrel, pistol-length gas system and a shot-peened Mil-Spec 8620 bolt carrier. It utilizes 7075-T6 aluminum receivers, 15in M-Lok handguard, Magpul MOE-K2 grip, and a Magpul CTR stock. This model has a Diamondback Black Gold lower receiver.