DIAMONDBACK FIREARMS DB15 5.56X45MM NATO SEMI-AUTO RIFLE W/ KNIGHT'S ARMAMENT COLD HAMMER FORGED BARREL BLANK At the heart of this AR-15 lies a premium chrome-lined, cold hammer forged barrel. This Knight's Armament and Diamondback Firearms collaboration begins with Knight's Armament providing their proprietary chambered, rifled, and chrome lined cold hammer forged barrel blank. Diamondback Firearms then finishes the profiling of the barrel and performs final assembly, resulting in an end product with exceptional accuracy and excellent longevity. Built for durability, the Carbon Series DB15 lower is machined from forged 7075-T6 aluminum and Mfg: Diamondback