Cmmg Bbl 300blk 16.1" Mr 4140cm Sbn

The CMMG Barrel 300 Blackout 16.1" Multi Role 4140 Chrome Moly is a precision-engineered upper receiver component purpose-built for subsonic and supersonic .300 Blackout precision builds. This 16.1-inch barrel arrives with a properly installed M4 barrel extension and factory headspace verification, eliminating guesswork during assembly and delivering a bolt-on solution for custom AR-platform rifle builders and gunsmiths.

The barrel features a 1:7 twist rate—the standard for .300 Blackout across the subsonic-to-supersonic velocity spectrum—machined from 4140 chrome moly steel for superior durability and heat resistance during sustained fire. The 5/8x24 thread pitch accommodates standard .300 Blackout suppressors and muzzle devices, while the carbine-length gas port with .750" gas block journal integrates seamlessly with standard M4-profile upper receiver assemblies. The multi-role profile balances velocity potential with manageable weight, making this barrel equally at home in compact, suppressed configurations or as a foundation for hunting builds. All sub-assemblies ship properly headspaced to SAAMI specification.

This barrel serves operators, precision shooters, and rifle builders who demand verified .300 Blackout performance without the labor of aftermarket headspacing. The 300 Blackout chambering has become the standard for suppressed short-range rifle systems in both tactical and civilian hunting contexts, and this CMMG barrel delivers the ballistic platform needed to unlock that performance. Weighing 2.25 lbs, it's suited for SBR builds, precision builds, or reconfigurable upper receivers where barrel swaps are planned.