Diamondback Firearms DB15 rifle uses a gas-impingement system and high quality CNC machined components. Features a 4140 chrome moly barrel, A3 Flattop upper receiver, carbine length gas system, 12" M-LOK rail, MOE grip, A2 Flash hider muzzle and a Magpul MOE Carbine stock. Made in the USA. This model comes with a compatible upper assembly chambered for 300 Blackout.