This CMMG Barrel Sub-Assembly (brand part number 30D810A) is an 8-inch .300 AAC Blackout barrel cut to a medium tapered profile and built for pistol-length AR platforms that need a short, reliable barrel for the caliber. CMMG machines it from 4140 chrome-moly steel and finishes it with a salt bath nitride treatment for corrosion and wear resistance, then times the pistol-length gas system to a .750-inch gas block for dependable cycling in a short-barreled build. The muzzle threads at 5/8-24 TPI to accept standard .30-caliber muzzle devices.

Key Specifications

• Chambered in .300 AAC Blackout.
• Measures 8 inches in barrel length.
• Rifled with a 1:7 twist rate.
• Machined to a medium tapered profile.
• Threaded 5/8-24 TPI.
• Weighs approximately 1.5 lbs.
• Runs a pistol-length gas system.
• Sized for a 0.750-inch gas block.
• Machined from 4140 chrome-moly steel.
• Finished with a salt bath nitride treatment.

Frequently Asked Questions

What gas system does it use? Pistol-length, sized for a 0.750-inch gas block.

What thread pattern is the muzzle? 5/8-24 TPI.

What’s the barrel weight? Approximately 1.5 lbs.

Buy the CMMG .300 AAC Blackout Barrel Sub-Assembly

Build a short, reliable .300 Blackout pistol upper on a barrel that’s already timed and finished. Order it from our CMMG lineup, part of our AR-15 barrels selection, at our Lubbock, Texas gun shop for fast, direct shipping.