Complete 16″ 300 Blackout Upper with 15″ Slim, Air Lite M-Lok Hand Guard This upper includes a 16″ barrel tipped with an A2 flash hider/suppressor threaded 5/8″-24. Barrel has a 1:8 twist. Reliable pistol gas system (with low-profile micro gas block) cycles all types of 300 Blackout ammo. This upper comes with an A3 upper receiver with forward assist and ejection port cover installed. Barrel and receiver have matching M4 feed ramps. Heavy duty M16 bolt carrier group and charging handle included. Comfortable 15″ free floating M-Lok hand guard. The gas system is pistol length allowing the trouble free use of all sub-sonic and super-sonic ammo. This high quality upper is a perfect fit on any mil-spec or multi-cal AR-15 lower. Swap the complete upper and you’re ready to shoot! Comes with the Barrier Defense lifetime warranty! ****Know your states laws when purchasing gun parts.****