US Patent 10168115 Mating bolt carrier and barrel extension

A mating bolt carrier and barrel extension, including at least some of a bolt carrier having a front face that includes one or more surface preparations or features formed at least partially thereon or therein; and a barrel extension having a rear face that includes one or more surface preparations or features formed at least partially thereon or therein, wherein at least a portion of the one or more surface preparations or features are capable of mating or interlocking with the surface preparations or features of the front face of the bolt carrier.