The CMMG Zeroed Lower Parts Kit (brand part no. 55CA642) upgrades an AR-platform/Mk4 lower build with CMMG’s Zeroed line of enhanced controls: an extended bolt catch, an adjustable 60/90 ambidextrous safety, and a mil-spec trigger group, all finished in black. Rather than a basic parts kit with generic small hardware, this is CMMG’s premium internals package, giving builders ambidextrous controls and a smoother trigger feel without sourcing each upgrade separately. It’s a strong option for anyone building a lower they intend to actually shoot hard, not just complete on paper.

Key Specifications

• Includes a Zeroed extended bolt catch with plunger, spring, and roll pin.
• Includes a Zeroed 60/90 adjustable ambidextrous safety.
• Includes a mil-spec trigger and trigger spring with disconnector, hammer, and retaining pins.
• Includes a Zeroed trigger guard with screw and roll pin.
• Compatible with the AR-platform/Mk4 lower receiver pattern.
• Finished in black.

Frequently Asked Questions

Does this kit include an ambidextrous safety? Yes, a Zeroed 60/90 adjustable ambidextrous safety is included.

What platform does this fit? AR-platform/Mk4 lower receivers.

Buy the CMMG Zeroed AR-Platform Lower Parts Kit

Upgrade your build with genuine CMMG Zeroed parts. Order it from our Lubbock, Texas gun shop for fast, insured shipping, and see our full AR lower parts selection.