The Midwest Industries Complete 16″ 5.56 Upper Receiver Assembly is ready to install on the mil-spec lower of your choice. Chambered in .223 Wylde, this rifle is ready to shoot military-type 5.56x45mm ammo or civilian .223 Remington with equal accuracy. The “pencil”-profile barrel won’t weigh you down. The Midwest Industries Complete 16″ 5.56 Upper Receiver Assembly comes with MI’s own lightweight, free float, M-LOK G3 handguard. It sports a two-port muzzle brake mounted on the 1/2100-023-932-28 threaded muzzle. 12.6″ M-LOK handguard for plenty of accessory-mounting versatility 7075 T6 forged aluminum upper receiver M4-type Mfg: Midwest Industries, Inc.