HM Defense HMBBCGAR15 HMB 223 Rem/5.56 NATO Bolt Carrier Groupt 4340 Hardened Steel Cam Pint 9130 Steel w/Black Nitride Finish

HM Defense AR-15 Bolt Carrier Group - Black NitrideThe HMB Bolt corrects a natural weak point in existing Mil-Spec M16, AR-10 & AR-15 bolts where the cam pin hole passes through the bolt. Under extensive use, including the stress of combat, a standard Mil-Spec bolt can fail at the cam pin hole location. 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 new patent-pending design eliminates the natural weak point of Mil-Spec bolts by significantly increasing the amount of metal (and strength) at the cam pin location. The result - No more broken bolts! Additionally, the HMB Bolt reduces contact between cam pin and firing pin, enabling smoother operation of firing pin, bolt lugs and aft gas rings. The new cam pin socket also retains lubrication for extended operations.BOLT CARRIER GROUP SPECIFICATIONSManufacturer: HM DefenseManufacturer Part #: HMB-BCG-AR15Type: Bolt Carrier GroupColor: BlackFinish: Nitride5.56 NATO - 223 Rem - 300 AAC9310 Steel4340 Hardened Steel Cam PinNitride Black Finish