
Availability: In Stock
The Proof Research .338 ARC barrel for AR-15 pistols brings precision and power to a compact platform. This 12-inch rifle-length profile carbon fiber barrel is engineered for shooters building or upgrading an AR-15 pistol chambered in .338 ARC—a potent intermediate cartridge that delivers rifle-class performance in a short-barrel configuration. Proof Research barrels are known for match-grade accuracy and durability, making this an ideal choice for dedicated AR pistol builders who demand serious capability in a handy package.
Built with a 1-in-8 twist rate, this barrel stabilizes the wide range of bullet weights that .338 ARC handloaders and manufacturers are developing for the cartridge. The pistol-length gas tube keeps the system optimized for the shorter platform while the .750-diameter gas journal provides straightforward compatibility with standard AR-15 pistol components. The 5/8-24 muzzle threads open the door to suppressors, flash hiders, and muzzle devices—practical add-ons for shooters who value both performance and hearing protection.
Proof's carbon fiber construction reduces barrel weight without sacrificing rigidity, a real advantage when you're working within the compact, high-recoil environment of a pistol-frame rifle. Whether you're assembling a dedicated range build, a short-range hunting pistol, or a truck gun, this barrel delivers the precision and reliability Proof is known for at a component level.
| Caliber | .338 ARC |
| Barrel Length | 12 inches |
| Twist Rate | 1-in-8 |
| Gas System | Pistol-length |
| Gas Journal Diameter | .750 inches |
| Muzzle Thread | 5/8-24 |
| Material | Carbon fiber |
This barrel is designed for AR-15 pistol platforms with a pistol-length gas system. Confirm your receiver and gas tube configuration match before ordering.
The 5/8-24 threads accept any suppressor or muzzle device with a 5/8-24 female thread—the standard for most .338 ARC and larger-caliber suppressors and brakes.
The 1-in-8 twist is optimized to stabilize the range of bullet weights available in .338 ARC, from lighter varmint rounds to heavier hunting and target projectiles.
This is a barrel component; you will need a compatible upper receiver, bolt carrier group, charging handle, and other AR-15 pistol components to complete your build.

SKU: 152744516 • Weight: 2oz




Availability: In Stock
The Proof Research .338 ARC barrel for AR-15 pistols brings precision and power to a compact platform. This 12-inch rifle-length profile carbon fiber barrel is engineered for shooters building or upgrading an AR-15 pistol chambered in .338 ARC—a potent intermediate cartridge that delivers rifle-class performance in a short-barrel configuration. Proof Research barrels are known for match-grade accuracy and durability, making this an ideal choice for dedicated AR pistol builders who demand serious capability in a handy package.
Built with a 1-in-8 twist rate, this barrel stabilizes the wide range of bullet weights that .338 ARC handloaders and manufacturers are developing for the cartridge. The pistol-length gas tube keeps the system optimized for the shorter platform while the .750-diameter gas journal provides straightforward compatibility with standard AR-15 pistol components. The 5/8-24 muzzle threads open the door to suppressors, flash hiders, and muzzle devices—practical add-ons for shooters who value both performance and hearing protection.
Proof's carbon fiber construction reduces barrel weight without sacrificing rigidity, a real advantage when you're working within the compact, high-recoil environment of a pistol-frame rifle. Whether you're assembling a dedicated range build, a short-range hunting pistol, or a truck gun, this barrel delivers the precision and reliability Proof is known for at a component level.
| Caliber | .338 ARC |
| Barrel Length | 12 inches |
| Twist Rate | 1-in-8 |
| Gas System | Pistol-length |
| Gas Journal Diameter | .750 inches |
| Muzzle Thread | 5/8-24 |
| Material | Carbon fiber |
This barrel is designed for AR-15 pistol platforms with a pistol-length gas system. Confirm your receiver and gas tube configuration match before ordering.
The 5/8-24 threads accept any suppressor or muzzle device with a 5/8-24 female thread—the standard for most .338 ARC and larger-caliber suppressors and brakes.
The 1-in-8 twist is optimized to stabilize the range of bullet weights available in .338 ARC, from lighter varmint rounds to heavier hunting and target projectiles.
This is a barrel component; you will need a compatible upper receiver, bolt carrier group, charging handle, and other AR-15 pistol components to complete your build.
SKU: 152744516 • Weight: 2oz
