American Tactical Upper 450 Bushmaster 16" Keymod Rail, Black Nitride - ATI 15MS450BM

This is a drop-in ready upper receiver assembly for AR-15 pattern rifles, not a standalone barrel. It features a forged aluminum upper receiver with a 16" barrel in 450 Bushmaster, 1:24 button cut rifling, black nitride finish, and includes a 15" free-floated KeyMod rail system, carbine-length gas system, A2 compensator, and bolt carrier group. Designed to fit any standard AR-15 pattern lower receiver.