CMMG 38BA423 Mk3 Bolt Carrier Group .308 Win/7.62x51 NATO AR-10 Black Phosphate Steel

The CMMG 38BA423 is a complete Mk3 bolt carrier group purpose-built for .308 Win / 7.62x51mm NATO AR-10 and LR-308 pattern rifles and pistols. Designed from the ground up as a high-pressure BCG, it gives your big-bore AR build the strength and reliability needed to run .308 Winchester ammunition with confidence.

The bolt is machined from 9310 steel with a black phosphate finish, while the carrier is forged from 8620 steel, chrome lined for extended service life, and finished in matching black phosphate. The extractor is cut from S7 tool steel for durability at the rim, and the bolt ships with the extractor, ejector, and gas rings already installed so it drops straight into a Mk3-spec upper.

Engineered for proper headspacing and reliable cycling with CMMG Mk3 and other LR-308 / AR-10 platform uppers, the 38BA423 delivers the corrosion resistance and lubricity needed for hard-use rifles and suppressed hosts alike.