This Upper Receiver Assembly is unique in that its barrel features a mid-length positioned gas block and mid-length handguard set. It is complete and ready to snap onto your Lower – just add the Rear Sight or Optic of your choice to the machined Picatinny Rail of the Receiver. The highly accurate 16″ Mid-length Barrel is Chrome Lined and machined from 4150 Chrome Moly Vanadium 11595E Steel. Rifling is 1 x 9″ Right Hand Twist. The barrel extension has the M4 style feed ramps. An A2 Flash Suppressor and Picatinny Railed Gas Block are fitted. The machined aluminum flat top Upper Receiver is complete with Bolt Carrier Assembly, Charging Handle, Forward Assist and Ejection Port Cover.