The CMMG Mk3 Bolt Carrier Group (CMMG part number 38BA423) is a complete BCG built for the AR-10-pattern Mk3 platform in .308 Winchester. It is manufactured from steel and finished in black phosphate for corrosion resistance, with a chrome-lined carrier that adds durability and eases cleaning over an uncoated finish. As a complete, ready-to-install unit, it is a straightforward drop-in for CMMG Mk3-pattern uppers rather than a parts kit requiring assembly.

Key Specifications

• Chambered for .308 Winchester, matching the CMMG Mk3 platform.
• Construction is steel.
• Finish is black phosphate for corrosion resistance.
• The carrier is chrome-lined.
• It ships as a complete, ready-to-install bolt carrier group.
• It is built for the CMMG Mk3 platform specifically.

Frequently Asked Questions

Is this BCG complete or a parts kit? It ships as a complete, ready-to-install bolt carrier group, not a parts kit requiring assembly.

What finish does this BCG have? It is finished in black phosphate over steel construction, with a chrome-lined carrier.

What platform is this BCG built for? It is built for the CMMG Mk3 platform in .308 Winchester.

Buy the CMMG Mk3 Bolt Carrier Group

Keep your CMMG Mk3 running with a genuine, complete replacement BCG rather than a mixed parts kit. Browse more of our AR-10 bolt selection and order from our Lubbock, Texas gun shop for fast, direct shipping.