CMMG MK4/AR15 STRIPPED LOWER RECEIVER FOR AR-15 Precision machined from forged 7075 T6 aluminum, the CMMG Mk4 AR15 lower receiver is the quality mil-spec lower ready to be the foundation for your next build. The Mk4 stripped lower comes standard in Armor Black Cerakote finish and can be assembled using any mil-spec Lower Parts Kit. SPECS Platform Mk4 Lower Receiver Mk4 Forged 7075 T6 Aluminum Finish Armor Black Cerakote Mfg: Cmmg