CMMG Mk4/AR15 Upper Receiver Assembly - Coyote Tan

The CMMG Mk4/AR15 Upper Receiver Assembly is built around a forged 7075-T6 aluminum housing and finished in a durable Coyote Tan Cerakote that matches CMMG's modern rifle and pistol-caliber lineup.

The Mk4 platform's key feature is its enlarged ejection port, engineered to reliably clear spent cases when running pistol-caliber AR-15 builds chambered in 9mm, 10mm, .40 S&W, and .45 ACP in addition to standard 5.56mm and .223 Remington uppers. M4 feed ramps are machined into the receiver for reliable feeding from a standard AR-15 magazine well.

This Assembly configuration ships ready to drop onto your lower receiver, with CMMG's ZEROED polymer dust cover pre-installed. This variant omits the forward assist for a clean, lighter profile. The upper is sold as a receiver housing and components only - no barrel, bolt carrier group, charging handle, handguard, or muzzle device is included - making it a solid starting point for a custom AR-15 rifle or pistol-caliber build.