CMMG Upper Receiver Assembly | Mk4/AR15 | 14.5 in | Armor Black

Made from aircraft-grade aluminum, the CMMG Mk4/AR15 Upper Receiver Assembly provides a streamlined foundation for a custom AR15 build. It ships with a ZEROED Polymer Dust Cover pre-installed and intentionally omits the forward assist for a cleaner profile. The unit is specified for 223 Rem/5.56 NATO and pairs with 14.5-inch barrels that use a 1:7″ rate of twist. This upper is suited to range training and precision-oriented custom builds where part selection and fit are priorities.

Product Specifications

• Manufacturer: CMMG.
• Model: Upper Receiver Assembly for Mk4/AR15 Armor Black.
• Compatible platform: Mk4/AR15.
• Caliber: 223 Rem/5.56 NATO.
• Barrel length: 14.5 inches.
• Rate of twist: 1:7″.
• Barrel material: Steel.
• Barrel finish: Matte black.
• Receiver material: Aircraft grade aluminum.
• Dust cover: ZEROED Polymer Dust Cover pre-installed.
• Forward assist: Omitted (no forward assist).
• Dimensions: 2.95 x 3.05 x 9.20 inches.
• Weight: 0.535 pounds.
• Shipping restriction: No direct ship to California.
• UPC: 810097506329.

This upper receiver assembly offers a reliable, purpose-built platform for a range-focused AR15 build. Its aircraft-grade construction and matte Armor Black finish deliver a durable base that accepts standard Mk4/AR15 components, while the pre-installed ZEROED dust cover and the omission of the forward assist keep the profile clean and build-friendly. Choose this upper when you want a straightforward, well-specified component that supports accuracy-focused and competition-oriented builds.