The Faxon Big Gunner Duty Barrel (brand part number 10A863P12NGQ) is a 12-inch 8.6 Blackout barrel machined for AR-10-pattern builds, developed in partnership with Q on this newer, larger-caliber cartridge. Faxon machines it from raw 4150 steel bar stock, then stress-relieves, air-gauge tests, and Magnetic Particle Inspects every barrel before cutting the 11-degree target crown that helps drive its accuracy. The barrel uses button rifling in the Big Gunner profile with a pistol-length gas system, a Salt Bath Nitride finish inside and out for corrosion resistance, and an M18x1.5 tapered-shoulder thread with the mounting adapter included. As a bare 12-inch barrel with no receiver attached, it is not itself a regulated NFA item — federal law only restricts total barrel length once a barrel this short is installed on a rifle-configured complete lower receiver.

Key Specifications

• Chambered in 8.6 Blackout for AR-10-pattern builds.
• Measures 12 inches in length.
• Machined from raw 4150 steel bar stock.
• Uses button rifling in the Big Gunner profile.
• Cut with an 11-degree target crown for accuracy.
• Finished with Salt Bath Nitride inside and out.
• Threaded M18x1.5 with a tapered-shoulder mounting adapter included.
• Cut with a 1:3 twist rate to stabilize 8.6 Blackout’s heavy subsonic bullet weights.
• Built with a pistol-length gas system and a standard DPMS Gen 1 .308 extension.
• Tested with air-gauge and Magnetic Particle Inspection for quality control.

Frequently Asked Questions

Is this 12-inch barrel an NFA item? No. A bare barrel with no receiver attached is not itself regulated by the NFA. Federal law only requires ATF registration and a tax-free transfer if a barrel this short is installed on a complete, rifle-configured lower receiver — installing it that way without registering the resulting firearm as an SBR is illegal, so plan your build configuration accordingly.

What gas system does this barrel use? A pistol-length gas system matched to the Big Gunner profile.

Buy the Faxon Big Gunner Duty 8.6 Blackout Barrel

Build out your 8.6 Blackout AR-10-pattern platform with a precision-inspected barrel. Order it from our Faxon Firearms lineup of AR barrels for fast, reliable shipping from our Lubbock, Texas gun shop.