CMMG LOWER MK4/AR15 BLK

Description

A stripped lower receiver is where an AR-15 build begins, and the CMMG Mk4 is designed for builders who want a mil-spec-compatible foundation without having to work around proprietary geometry. The Mk4 pattern follows standard AR-15/M4 dimensions throughout, which means it accepts any mil-spec lower parts kit and feeds from standard AR-15/M4 pattern magazines — no fitment surprises, no chasing down platform-specific components.

The receiver is precision machined from forged 7075-T6 aluminum. Forging aligns the grain structure of the aluminum through compression rather than cutting across it, which produces a denser, more fatigue-resistant part than a billet receiver cut from plate. For a lower receiver that houses the trigger group and bears the stress of the buffer and action cycling, that matters over the long term.

The finish is CMMG’s Armor Black Cerakote. Cerakote is a polymer-ceramic coating that bonds to the metal surface rather than sitting on top of it, giving it better abrasion and corrosion resistance than a simple anodize while adding negligible thickness to the part — tight-fitting components still fit.

Because this ships as a stripped receiver, you have full control over every internal component from the trigger group to the safety selector. That makes it a practical starting point for a purpose-built rifle, whether you are assembling to a specific trigger weight, selector configuration, or stock geometry that a factory-complete lower would not give you.