This M4 Barreled Upper Receiver Assembly based on our SRC Rifle is compliant with regulations for use in States with restrictions on flash hiders. It is complete and ready to snap onto your Lower. The accurate 16” M4 profile barrel is chrome lined and machined from 4150 Chrome Moly Vanadium 11595E Steel with M4 feed ramps and is rifled 1 x 9” right hand twist for optimum accuracy with a wide range of .223 Rem. / 5.56mm NATO ammunition. The barrel includes a permanently affixed A2 birdcage style compensator. Its bayonet lug has been machined off. The Gas Block is our Picatinny Rail type – ready for the addition of accessory front sight if you choose. The machined aluminum flat top Upper Receiver is complete with Bolt Carrier Assembly, Charging Handle, Forward Assist and Ejection Port Cover.