Brownells and KAK Industry have collaborated to develop a high-performance complete upper receiver assembly, offering exceptional value. This premium assembly includes a chrome-lined barrel, a chrome-lined phosphate K-Spec enhanced bolt carrier group (BCG), a Brownells exclusive PentaComp muzzle device and a robust free-float KAK Industry M-LOK handguard. Manufactured entirely in the United States, it ensures years of reliable service. The K-Spec down vent BCG is engineered for superior reliability, incorporating slotted angled carrier rails, dual ejectors and downward gas vents that channel gas beneath the carrier, minimizing exposure to the shooter. This feature is particularly advantageous for suppressed shooting with a traditional baffle suppressor, marking a significant advancement in performance. 7075-T6 forged upper receivers Intermediate length gas system 1/2-28 muzzle threads featuring the Brownells exclusive PentaComp device Chrome-lined phosphate K-SPEC enhanced bolt carrier group (BCG) Enhanced charging handle with large billet latch Barrel specifications - 13.9 inches 4150 CrMoV chrome-lined, featuring a 1:7 twist rate and subjected to dual stress relief processes 13 inches M-LOK handguard featuring a robust barrel nut