.300 Blackout Barrels by AT3 Tactical
A .300 Blackout barrel makes swapping to a heavier hitting cartridge in your favorite rifle simple. This 4150 CMV barrel features a medium profile, providing plenty of support for mounting a suppressor, without feeling cumbersome in the field. It also gets a black nitride finish for corrosion resistance, and has M4 feed ramps for optimal reliability.
This barrel uses a .750″ diameter gas block, plus a Pistol length gas tube, both of which you can snag here. If you’re looking to start fresh with a complete upper assembly, check out our selection of upper and handguard combos! For this barrel, we’d recommend a handguard at least 12 to 15 inches long for shooter comfort, and space for accessories.











