CMMG Lower Mk4/ar15 5.56 NATO Cerakote

The CMMG Lower Mk4/AR15 Black (SKU: CMMG55CA102-AB) is a stripped lower receiver purpose-built as the foundation for mil-spec AR-15 builds in .223 Remington or 5.56 NATO. Precision-machined from 7075 T6 aluminum forging and finished in durable Cerakoted Armor Black, this lower receiver meets military specifications and is ready to accept any mil-spec lower parts kit, making it the logical starting point for operators, competitive shooters, and build enthusiasts who demand uncompromising material quality.

7075 T6 aluminum is the aerospace-grade alloy used in critical load-bearing applications where strength-to-weight ratio is non-negotiable. This forging provides superior dimensional stability and impact resistance compared to conventional aluminum, ensuring consistent receiver geometry across thermal cycling and thousands of rounds downrange. The Cerakote Armor Black finish offers corrosion resistance and aesthetic durability in field conditions, protecting the receiver from moisture and salt exposure without adding measurable weight. At 0.69 lbs, the stripped lower contributes minimal mass to the overall platform while maintaining the structural integrity required for reliable cycling and component retention.

This receiver suits armorers, tactical operators building duty rifles, law enforcement agencies conducting platform refreshes, and civilian competitors constructing precision or carbine configurations. The mil-spec profile ensures drop-in compatibility with standardized upper assemblies, barrel extensions, and trigger groups, eliminating fitment variables. Whether assembling a patrol carbine, range platform, or specialized build, the CMMG Mk4 lower receiver provides the dimensional accuracy and material resilience needed for dependable operation across training cycles and operational demand.