One Horse .300 BLK Medium Contour AR-15 Barrel - Pistol-Length - 10.5"

The .300 Blackout was designed for exactly this — a 10.5-inch barrel that cycles both supersonic and subsonic loads reliably, whether you're running it suppressed or unsuppressed. The One Horse 10.5-inch .300 BLK barrel brings pistol-length gas, black nitride, and mil-spec 4150 construction to compact builds where the cartridge's potential is fully realized.

The One Horse .300 BLK 10.5-inch Barrel is a compact AR-15 barrel chambered in .300 Blackout, machined from 4150 steel with a black nitride finish and medium profile on a pistol-length gas system, designed for SBR and pistol builds running both supersonic and subsonic .300 BLK ammunition.

Three features make this barrel purpose-built for the .300 BLK platform at 10.5 inches. The pistol-length gas system is specifically tuned for the .300 Blackout cartridge in a short barrel, providing reliable cycling across the full spectrum of .300 BLK loads — from 110-grain supersonic ammunition to 220-grain subsonic rounds — without the over-gassing issues that can occur when a longer gas system is used with suppressed subsonic loads. The 1:7 twist rate stabilizes the heaviest .300 BLK subsonic projectiles reliably, which is critical for suppressed builds where 200-to-240-grain bullets are the primary load. Black nitride finish protects the bore from the accelerated carbon fouling that suppressor use generates, simplifying maintenance on a platform that will see high round counts in suppressed configuration.

Compatible with mil-spec AR-15 upper receivers and pistol-length gas systems. 5/8x24 threaded muzzle for suppressor compatibility.

4150 steel. Black nitride finish. Medium profile. Made in the USA.

Purpose-built for suppressed .300 BLK SBR and pistol builds, home defense configurations, and tactical applications where 10.5 inches of .300 Blackout in a compact package is the objective.

By One Horse. Made in the USA. Standard manufacturer warranty applies.