The CMMG 16.1-inch .300 Blackout Multi Role Barrel Sub-Assembly (brand part no. 30DF80A) is ideal for building a custom AR-15 upper group in .300 AAC Blackout. CMMG constructs the barrel from 4140 chrome moly steel with a salt bath nitride finish and cuts 5/8×24 muzzle threads, the larger thread pitch .300 Blackout’s bigger bore calls for compared to a 5.56 barrel. Built in the Multi Role profile with a carbine-length gas system, it ships with the M4 barrel extension already properly installed, saving builders a separate fitting step. For builders assembling a versatile .300 Blackout upper for both supersonic and subsonic use, this AR15 barrel is ready to install.

Key Specifications

• Chambered in .300 AAC Blackout.
• Barrel length measures 16.1 inches.
• Rifling twist is 1:7.
• Built in CMMG’s Multi Role profile.
• Machined from 4140 chrome moly steel.
• Finished with a salt bath nitride coating for corrosion resistance.
• Muzzle threads are 5/8×24, sized for .300 Blackout’s larger bore.
• Built with a carbine-length gas system.
• Ships with the M4 barrel extension properly installed.

Frequently Asked Questions

Why does this barrel use 5/8×24 threads instead of 1/2-28? .300 Blackout’s larger bore diameter calls for the bigger 5/8×24 thread pitch rather than the 1/2-28 standard on 5.56 barrels.

Does this barrel come with the extension installed? Yes, it ships with the M4 barrel extension properly installed.

Buy the CMMG 16.1in .300 Blackout Multi Role Barrel Sub-Assembly

A pre-installed extension and properly-sized threading give builders a straightforward path to a versatile .300 Blackout upper. Order it from our Lubbock, Texas gun shop for fast, insured shipping.