CMMG 30DF80A Barrel Sub-Assembly 300 Blackout 16.1" 1:7 4140 Chromoly Black Nitride AR-15

The CMMG 30DF80A Barrel Sub-Assembly is purpose-built for assembling a custom AR-15 upper chambered in 300 Blackout (also known as .300 AAC Blackout / 7.62x35mm). Cut from 4140 Chromoly steel and finished in a tough Black Nitride coating, this 16.1" barrel uses CMMG's versatile Multi Role (MR) profile to balance heat dissipation and carry weight for general-purpose carbine use. A 1:7" twist stabilizes the broad spread of supersonic and subsonic projectiles that make 300 BLK such a flexible round for both suppressed and unsuppressed shooting.

This sub-assembly ships ready to install. Each CMMG barrel comes with a properly fitted M4 barrel extension already installed and is headspaced at the factory, so the builder only needs to pin it to a compatible upper receiver and complete the build with a gas system, handguard, bolt carrier group, and muzzle device. The gas port is positioned for a standard carbine-length gas system, supporting reliable cycling across a wide variety of 300 AAC Blackout loads, while the Nitride finish helps both the bore and exterior resist wear and corrosion during extended range use.

Sights: none installed, leaving the build clean for the shooter's preferred optic or iron-sight setup. This listing is for the barrel sub-assembly only; the upper receiver, handguard, bolt carrier group, gas tube, and muzzle device are sold separately.