Description
The Faxon Big Gunner AR10 Barrel is a 16 inch Duty Series AR-10 barrel chambered in 8.6 Blackout with an extraordinary 1:3 twist. It uses a standard DPMS Gen 1 .308 extension, so it drops into a conventional large frame upper.
Why a 1:3 Twist
Almost nothing else on the market spins a bullet this fast. The 8.6 Blackout was designed around it deliberately: a very fast twist stabilises heavy .338 calibre subsonic projectiles that a conventional rate simply cannot, and it makes those bullets behave dramatically on impact.
That is the whole argument for the cartridge. It gives a large frame AR a heavy, quiet, hard hitting subsonic option, with supersonic loads available when you want reach instead.
Faxon Big Gunner AR10 Barrel Profile
The Big Gunner is Faxon’s large frame version of the Gunner profile: slimmed down under the handguard where mass does nothing useful, and left thicker out past the gas block where rigidity and heat capacity matter. At 2.2 pounds it keeps an AR-10 build from becoming unwieldy.
The steel is 4150 chrome moly vanadium, button rifled, and finished in salt bath nitride QPQ inside and out. Nitride hardens the bore surface rather than sitting on top of it, so it cannot chip or flake, and it makes cleaning far easier.
Threads, Gas and Extension
The muzzle is threaded M18x1.5 with a tapered shoulder, which is the standard 8.6 Blackout suppressor interface, and an adapter is included. A carbine length gas system runs on an .875 inch gas block journal 1.9 inches long.
The barrel extension is a standard DPMS Gen 1 .308 unit in black oxide, so the barrel fits ordinary large frame uppers rather than requiring a proprietary receiver. Every barrel is magnetic particle inspected, and the muzzle wears an 11 degree target crown.
Subsonic and Supersonic
Subsonic 8.6 Blackout loads run 300 grains and heavier at around 1,000 feet per second, which is where the 1:3 twist earns its keep. Supersonic loads in the 170 to 210 grain range give the cartridge useful reach for hunting, and the same barrel handles both without any change of parts.
Specifications
- Manufacturer: Faxon Firearms
- Platform: AR-10, Duty Series
- Item Number: 10A863C16NGQ
- Caliber: 8.6 Blackout
- Length: 16 in.
- Twist: 1:3
- Profile: Big Gunner
- Material: 4150 chrome moly vanadium
- Rifling: Button rifled
- Finish: Salt bath nitride QPQ, inside and out
- Gas system: Carbine length
- Gas block diameter: .875 in., 1.9 in. journal
- Muzzle threads: M18x1.5 tapered shoulder, adapter included
- Extension: DPMS Gen 1 .308, black oxide
- Crown: 11 degree target crown
- Weight: 2.2 lbs.
- Inspection: Magnetic particle inspected
- UPC: 816341026384
Building Around This Barrel
An 8.6 Blackout upper uses standard .308 AR-10 bolts and magazines, so most of the parts you already own carry over. You will need an .875 gas block and a carbine length gas tube, and Faxon notes that function and tuning vary with ammunition, buffer system and suppressor, so an adjustable block is worth planning for.
Why Buyers Choose the Faxon Big Gunner AR10 Barrel
The Faxon Big Gunner AR10 Barrel is one of the most accessible ways into a cartridge that otherwise requires a complete rifle purchase. It uses a standard DPMS extension, standard .308 bolts and standard magazines, and Faxon makes and inspects it in Ohio.
Who Should Buy It
Suppressor owners who want a genuinely heavy subsonic option, hog and predator hunters, and AR-10 builders looking for something well outside the usual .308 and 6.5 Creedmoor choices.
Be aware of the caveats. At the time of writing 8.6 Blackout is not SAAMI certified, so use appropriate caution particularly with reloaded ammunition. Always verify headspace with proper gauges and confirm muzzle device alignment before firing.
Full specifications are published by Faxon Firearms. Gas blocks and other build components are listed alongside the rest of our catalog.
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