CMMG Receiver Extension and Stock Kit Carbine Mk3

The CMMG Receiver Extension and Stock Kit Carbine Mk3 provides a comprehensive solution for shooters looking to finalize the lower receiver group of their large-frame AR platform. Designed specifically for those building or upgrading a .308 Winchester or 7.62x51mm NATO rifle, this kit ensures that the critical interface between the shooter and the firearm is both reliable and adjustable. Whether you are assembling a new build for long-range precision or a duty-ready carbine, this kit is available for sale to eliminate the guesswork often associated with the heavy recoil of the Mk3 platform.

This kit features a 6-position receiver extension, also known as a buffer tube, which allows for precise length-of-pull adjustments to accommodate different body types or the use of body armor. Included in the package is a .308 carbine buffer assembly and a specialized .308 carbine action spring, both engineered to manage the increased bolt carrier group mass and higher pressures of larger calibers. The 6-position buttstock assembly provides a stable cheek weld and robust construction to withstand the rigors of field use while maintaining a lightweight profile.

Optimized for the CMMG Mk3 and other compatible .308 AR-style lower receivers, this kit is an essential purchase for those seeking mil-spec quality and performance. Installation is straightforward when combined with a standard lower parts kit, making it a favorite for armorers and DIY enthusiasts who demand consistent cycling and durability. When you buy this assembly, you are investing in a proven system that balances recoil management with ergonomic flexibility, meeting the high specifications required for diverse tactical environments.