The Fail Zero Full-Auto Bolt Carrier Group (brand part number FZM16401NHBLACK) is a complete, mil-spec M16-profile carrier built for 5.56mm AR-15 and M16 uppers that need a genuine full-auto-cut bolt carrier. Fail Zero machines the carrier from steel and treats every wear surface with its EXO nickel boron coating under a black topcoat, cutting friction and making the action easier to clean than a standard phosphate finish. The group ships complete and ready to drop into most mil-spec M16, M4, and AR-15 upper receivers, with a 5.56/.223-compatible bolt and extractor, staked carrier key, cam pin, and firing pin already installed. It’s a straightforward upgrade for shooters who want a smoother-running, easier-to-maintain carrier group.

Key Specifications

• Machined to the M16 full-auto carrier profile.
• Built for 5.56mm/.223-compatible bolts and extractors.
• Treated with Fail Zero’s EXO nickel boron coating for reduced friction and easier cleaning.
• Finished with a black topcoat exterior.
• Machined from steel for durability.
• Drops into most mil-spec M16, M4, and AR-15 uppers.
• Ships with a staked carrier key installed.
• Includes the cam pin as part of the assembly.
• Includes the firing pin as part of the assembly.

Frequently Asked Questions

What finish is on this carrier group? Fail Zero’s EXO nickel boron coating under a black topcoat, which reduces friction and makes cleaning easier than a standard phosphate finish.

Will it fit my AR-15 upper? Yes, it’s a drop-in fit for most mil-spec M16, M4, and AR-15 uppers.

Does it come complete? Yes, it ships with the bolt, extractor, cam pin, carrier key, and firing pin already installed.

Buy the Fail Zero Full-Auto Bolt Carrier Group

Upgrade to a smoother-cycling, easier-to-clean carrier group built to mil-spec tolerances. Order it from our Fail Zero lineup, part of our AR bolt carrier groups selection, at our Lubbock, Texas gun shop for fast, direct shipping.