Faxon Duty Series 12" Big Gunner, 8.6 Blackout, Pistol Length, 4150, Nitride, AR-10 Barrel

(6 reviews)
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Welcome To The Future

Faxon Firearms is proud to partner with Q on the development of barrels for their revolutionary new round, 8.6 Blackout (8.6 BLK).
With barrels employing an impressive 1:3 twist rate, 8.6 BLK channels rotational energy to increase energy on-target.

Learn more about the round by Clicking Here.

As with all Faxon Barrels, these 8.6 BLK barrels are machined from raw bar stock in our greater Cincinnati Facility. Faxon 8.6 BLK barrels are fully stress-relieved, air-gauge tested, Magnetic Particle Inspected, and 11-degree target crowned to ensure superior accuracy. Constructed of 4150 CMV, each barrel goes through a battery of tests at each operation until finished in Nitride and final inspected.

All Faxon Barrels are individually checked for headspace by precision custom hardened gauges and are backed by the Faxon Lifetime Guarantee.

Consumer Note:
At the time of release, 8.6 BLK is not SAAMI certified. Please use appropriate caution while firing and when using reloaded ammunition.
Learn more and find load data provided by Q by Clicking Here.

  • Barrel Material: 4150 CMV
  • Rifling: Button
  • Barrel Caliber: 8.6 BLK
  • Barrel Twist: 1:3
  • Barrel Length: 12"
  • Barrel Profile: Big Gunner
  • Barrel Gas System: Pistol
  • Inside Finish: Salt Bath Nitride
  • Outside Finish: Salt Bath Nitride
  • Muzzle Thread: M18x1.5, tapered shoulder (adapter included)
  • Gas Block Diameter: .875"
  • Gas Block Journal Length: 1.9"
  • Barrel Extension: Standard DPMS Gen 1 .308 Extension, Black Oxide
  • Weight: 2.0 lbs
  • Magnetic Particle Inspected
  • 11° Target Crown


We have noticed inconsistencies with 8.6 BLK ammunition available on the market. Ammunition that does not match cartridge print below cannot be guaranteed to function in our rifles or barrels.


Using cartridges made specifically for semi-auto rifles may cause light primer strikes in bolt action rifles due to hard primers.


If you have any questions, please contact customerservice@faxonfirearms.com.

8.6 BLK Cartridge Drawing

Barrel Caliber:
8.6 BLK
Barrel Profile:
Big Gunner
Barrel Material:
4150 CMV
Outside Finish:
Salt Bath Nitride
Barrel Twist:
Muzzle Thread:
Gas Block Diameter:
Gas Block Journal Length:
Barrel Weight:
2.0 lbs
Barrel Length:
Barrel Length Range:
11.5" - 14.5"


  • 5
    12" 8.6 Blackout

    Posted by We Talk Guns on Dec 15th 2022

    The barrel itself is top notch. Nice and heavy and I can't find a thing wrong with it. After 2 months of shopping and meticulously putting parts together I have finally built my AR pistol and gotten a bit of ammo from Gorilla ammunitions. Took it out to the range today and to my surprise this thing has WAY less recoil and retort/noise than I was expecting. Shoots like an absolute dream. I've only shot subsonic ammo so far so maybe with the super sonic ammo it's have a little more flare and kick to it but from what I've shot so far, great stuff indeed.

  • 5

    Posted by Scott on Nov 10th 2022

    Been actively building and re-barreling all types of firearms for quite some time and was really impressed with the fit and finish of this barrel.

  • 5
    Faxon 12" Big Gunner 8.6 BLK barrel

    Posted by AlanD on Sep 1st 2022

    So glad to see Faxon come out with these and be on top of this new arising market. I wanted the 12" as most work seems to be done with it at the moment. Like all the Faxon product I have purchased it's top quality and having a Faxon bolt ensures everything will work together.

  • 5

    Posted by David on Aug 25th 2022

    Fit and finish are phenomenal, slides tightly into upper. Everything you could ask for in an 12" 8.6 blk barrel.

  • 3

    Posted by Hart Johnson on Jul 2nd 2022

    Disappointed tht the barrel doesn’t come dimpled, also felt Faxon should offer readily available thread adapters for the muzzle, not everyone uses a suppressor. The twist rate for some is undesirable. An offering of a slower twist rate such as 1/7 would enhance desirability due to cost of monolithic projectiles. Overall quality and build tho is excellent and up to Faxon standards. In time I can see these factors reimagined which will help the cartridge succeed.

  • 5
    FAXON 12" BIG GUNNER, 8.6 BLK Barrel

    Posted by Jeremy on Jun 15th 2022

    Craftsmanship is impeccable, can’t wait to start my next build with it.