Stern Defense Bolt Assembly Features The Stern Defense Bolt Assembly is machined from 8620 AISI steel and finished with a Mag-Phosphate coating that resists wear and corrosion through heavy use. It is built to fit Mil-Spec and Glock pattern upper receivers chambered in .45 ACP giving builders a drop-in option for completing an AR15/M16 pistol caliber carbine conversion. The bolt functions with Colt SMG and Glock magazines so shooters already invested in either magazine ecosystem can run their preferred mags without modification. It is also fully compatible with standard AR15/M16 charging handles keeping the rest of the upper assembly unchanged during the swap. Every bolt ships fully assembled with all sub-components installed including the firing pin firing pin spring retaining pin extractor and extractor spring so there is no additional parts kit to source. Proprietary center and roll pins are included as part of the assembly matching the tolerances Stern Defense engineered for this bolt. The design incorporates a geometry that caters to single stage triggers with short resets helping the gun run smoother and reset faster shot to shot. At 15.50 oz this bolt assembly is a straightforward reliable upgrade for anyone building or maintaining a .45 ACP AR15/M16 pattern carbine. Stern Defense Bolt Assembly Specifications Manufacturer: Stern Defense Model: Bolt Assembly Type: Bolt Caliber: .45 ACP Compatible Hosts: AR15 / M16 Material: 8620 Steel Finish: Manganese Phosphate Weight: 15.5 oz Available At: GrabAGun