Brownells has introduced big bore AR-15 barrels chambered in .458 SOCOM and .450 Bushmaster. The barrels for both caliber options come with the bolts and three-chamber muzzle brakes. Apparently these are custom profile barrels made by Faxon Firearms specifically for Brownells. In a recently published new products announcement video, Brownells’ employee Paul Levy says: “these are specific profiles that we requested from Faxon“. You can find that video embedded below.

Overall, the two barrels have virtually identical features with minor differences. Let’s take a closer look at each of them.

Brownells .458 SOCOM AR-15 Barrel

The .458 SOCOM barrel is made of 4150 mil-spec steel. These are 16″ button rifled barrels. After being machined from a rifled barrel blank, the barrels then get stress relieved and nitrided. These barrels are also magnetic particle inspected.

Brownells .458 SOCOM barrels have 1:14 twist rate and 11-degree muzzle crown. Although Brownells doesn’t specify the thread pitch of the muzzle threads, I think it is most likely 11/16×24 TPI because big bore Faxon Firearms barrels are threaded with that thread pitch. The gas block portion of these barrels has .750 diameter.

Muzzle brakes that come with new Brownells big bore AR-15 barrels look to have the Faxon MUZZLOK attachment systems. The latter consists of a separate lock nut at the base of the muzzle device which allows to time and install the muzzle device without using a crush washer or shims.

The whole package including the barrel, bolt and muzzle brake is listed on Brownells website at $309.99.

Brownells .450 Bushmaster AR-15 Barrel

As mentioned above, the .458 SOCOM and .450 Bushmaster barrels share most of the features. They are made of the same material and have the same finish/surface treatment. The .450 Bushmaster barrels also have 16″ length and perhaps the only difference is that the .450 Bushmaster barrels have 1:16 twist rate.

The price for the .450 Bushmaster barrel is also $309.99.

Images from www.brownells.com