STERN DEF BCG 9MM BU9 NIB ECHO FOR GLOCK CUT UPPERS/MAGSMade with 8620 AISI steel and boasting a NIB Mag phosphate finish, the Stern bolt fits into Mil Spec and Glock pattern upper receivers. It functions with Colt SMG, Glock magazines and it's fully compatible with standard AR15 M16 charging handles. Comes fully assembled with all sub components installed, including firing pin spring retaining pin, extractor, and extractor spring. Also included in bolt assembly is a propriety center and roll pins. Our 9mm