Also see our dedicated URGI upper page for Geissele MK16-railed SOPMOD Block II configurations.
Shop clone-correct CQB, SBR, MK18, and M4A1 upper receiver groups built to mil-spec. Includes Geissele URGi, Daniel Defense CQBR, and Colt-correct configurations for 10.3", 11.5", and 14.5" builds.