CMMG 30D120A Barrel Sub-Assembly 300 Blackout 16.10" 1:7 Black Nitride AR-15

The CMMG 30D120A Barrel Sub-Assembly is a purpose-built 16.10" replacement barrel for the AR-15 platform, chambered in 300 AAC Blackout (7.62x35mm). Designed to drop into a custom upper build, every CMMG Barrel Sub-Assembly is properly headspaced and ships with an installed M4 barrel extension, saving time at the bench and getting your upper into service faster.

Cut from 4140 Chromoly Steel and treated with a durable Black Nitride (Salt Bath Nitride) finish, the barrel's surface is hardened for improved wear resistance and corrosion protection in the field. A 1:7" rifling twist is well-matched to the wide range of supersonic and subsonic bullet weights used in 300 Blackout, and the Medium Taper Profile keeps weight manageable without sacrificing accuracy. Sized as a Carbine Length barrel at 16.10", this barrel pairs cleanly with a standard mil-spec carbine gas system for a reliable cycling AR-15 upper.

No iron sights are installed, leaving the top of the barrel free for the handguard and sighting system of your choice. Pair it with the upper receiver parts of your choosing to assemble a quiet, suppressed subsonic 300 BLK build, a heavy-bullet hunting rig, or any AR-15 upper you want to tailor around the versatile 300 Blackout cartridge.