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 your choice of seven Cerakote finishes and can be assembled using any mil-spec Lower Parts Kit. If you want to add some customization to your next AR build, consider upgrading to one of 10 different cerakote color options and pairing the Mk4 stripped lower with our Gunbuilder's Lower Parts Kit and picking out the Trigger Guard, Pistol Grip, and Fire Control Group to make your project whatever you imagine.