CMMG Receiver Extension and Stock Kit A1 Mk3

The CMMG Receiver Extension and Stock Kit A1 Mk3 is a drop-in replacement buttstock assembly designed for AR-platform rifles requiring mil-spec compatibility and reliable field performance. This kit serves operators, military personnel, and civilian shooters who need a no-nonsense control system that restores or upgrades their carbine's ergonomics and buffer tube assembly. The A1 Mk3 configuration balances traditional AR design principles with modern manufacturing tolerances, making it an ideal choice for those maintaining or rebuilding 5.56 NATO or .223 Remington platforms.

This receiver extension and stock assembly features mil-spec tube dimensions and A1-pattern stock geometry, engineered to mate securely with standard AR-15 lower receivers without modification. The kit includes all necessary components—receiver extension (buffer tube), spring, buffer weight, and A1-profile buttstock—delivered as a complete system to eliminate sourcing individual parts. The A1 stock profile provides a shorter length of pull compared to modern commercial adjustable systems, making it particularly suitable for shooters in tactical body armor, those preferring classic rifle ergonomics, or anyone building a compact carbine configuration. Precision machining ensures consistent fit and function across repeated installation cycles.

Law enforcement armorers, military unit supply personnel, and AR platform enthusiasts benefit most from this complete kit format, as it eliminates compatibility guesswork during field maintenance or build operations. Installation requires only standard AR-15 tools and takes minutes on any lower receiver with a properly sized buffer tube area. The A1 Mk3 is fully compatible with mil-spec buffer systems and fits all standard AR lowers with 1.14-inch diameter receiver extension holes. For shooters restoring vintage configurations, training rifle setups, or maintaining fleet consistency across multiple weapons, this CMMG offering delivers proven reliability without unnecessary features or cost.