HM Defense HMBAR15 HMB  223 Rem/5.56 NATO Bolt Assembly w/4340 Hardened Steel Cam Pin Fits Drop In Bolt Mil-Spec Carriers, 9310 Steel w/Black Nitride Finish

The HMB bolt by HM Defense eliminates the pass through cam pin hole and replaces it with a cam pin socket and tapered cam pin design. This patented design eliminates the natural weak point of Mil-Spec bolts by significantly increasing the amount of metal at the cam pin location. It is 100% compatible with Mil-Spec M16 & AR-15 BCGs and can installed as a drop-in bolt replacement in any existing M16 or AR-15 rifle.