Bushmaster F1007571 450BMSt Upper Assembly

Add the hard hitting punch of the 450 Bushmaster to your Bushmaster lower receiver instantly. AR type gas operating system drastically reduces recoil for excellent second shot control. Aluminum forearm free floats the barrel optimum accuracy. Heavy barrel is hard chrome lined in bore and chamber for exceptional durability and features 1 in 24 twist rifling optimized for the .450 bullet. Includes 5 round .450 specific magazine.