8.6 Blackout: 300 BLK’s Big Brother

8.6 Blackout Hornady
July 13, 2023  
Categories: Guns
Tags: Ammo

The 8.6 Blackout cartridge (8.6 BLK) is an interesting round. It was developed by Kevin Brittingham of Q in collaboration with a handful of ammunition manufacturers. It was originally intended mostly for the AR10 and Remington 700 platforms, but since then has been discussed as an option in other weapons. We’re going to tell you about the caliber and then where you can find 8.6 Blackout ammo for sale. 

Shooting the 8.6 Blackout cartridge.

This article about the 8.6 Blackout cartridge might be from the archives, but it remains relevant.



8.6 BLK has been likened to 300 Blackout, albeit on a larger scale, i.e., “300 BLK’s big brother,” and is occasionally referred to as the “8.6 Creedmoor”. The most common weapons chambered in this cartridge are (as of this writing) available via Faxon Firearms – there are others, including some from Q.

8.6 BLK vs 300 Blackout

Interestingly, the barrels mostly utilize a 1:3 twist rate (though there are some reportedly in 1:4).

8.6 BLK Gif

Barrels for the 8.6 BLK cartridge line were initially manufactured by Faxon, as were lower receivers. Whether that company will be the only ones to build for 8.6 Blackout remains to be seen, but it seems doubtful. If 8.6 BLK sees anything close to the success of the 300 Blackout then other brands will almost certainly get in on it.

Features of the 8.6 Blackout Cartridge

  • 338 Subsonic load, based around the 300 grain Sierra Match King
  • Similar to 338 Federal; however, the case was shortened to work reliably with gas guns without modification to mags. 
  • Fits AR10 frame long guns
  • It uses Standard 308 Mags
  • Low-Pressure Cartridge
  • Utilizes a shortened 6.5 Creedmoor case for the use of subsonic and high BC projectiles
  • Current Ammo Companies in Development: Gorilla, Hornady, Black Hills, and Discreet Ballistics


8.6 Blackout Ballistics

8.6 Blackout Load Data



8.6 Blackout for Sale

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Check 8.6 BlK Prices & Availability




Faxon on the 8.6 BLK Cartridge

Faxon Firearms has previously shown several 8.6 Blackout loads with a 300-grain bullet and a 210 grain Barnes TTSX bullet. These loads are still in development but should become commercially available in the foreseeable future.

The following come from a Faxon Firearms Q&A. 

8.6 BLK – what is it?

The 8.6 Blackout is widely spoken of as the “big brother” of 300 Blackout. The new caliber, developed by Q, completely re-imagines energy on target by using a faster twist rate – 1:3, compared to the popular twist rates of 1:7 and 1:8 for calibers like 5.56 NATO and 300 BLK.

When paired with a suppressor, these 300 grain bullets are as quiet as a .22. Plus, with the 1:3 twist, the bullet goes further and impacts harder than your traditional 1:7 twist bullet. The extra rotation is giving the bullet more spin, allowing it to travel further with more punch and expand at a lower velocity.

What about the round itself?

It’s a low-pressure cartridge utilizing a shortened 6.5 Creedmoor case, for use of subsonic and high BC 338 projectiles. Currently, Gorilla, Hornady, Black Hills, and Discreet Ballistics are in the process of developing ammunition in this caliber. And no, you won’t need any special mags for this ammo – it will fit in a standard 308 mag.

8.6 Blackout Hornady

8.6 Blackout rounds and brass. Early cartridges include 285-350 grain subsonic and 160-225 supersonic.


You should also read: Determining the best 8.6 Blackout barrel length


What kind of barrels is Faxon making, then?

We’ll have our own 8.6 BLK barrels for both AR-10 and Remington 700 platforms. The full offering (for now) will be:

Remington 700 Platform:

  • 8″ Light Palma, Remage style with 1:3 twist
  • 12″ Light Palma, Remage style with 1:3 twist
  • 16″ Light Palma, Remage style with 1:3 twist

AR-10 Platform:

  • 8″ Big Gunner with 1:3 twist
  • 12″ Big Gunner with 1:3 twist
  • 16″ Big Gunner with 1:3 twist


So… is Faxon making 8.6 BLK guns?

As of right now, no, we are not. We’re just making the barrels. However, you’ll be able to build yourself an awesome 8.6 gun with some incredible parts from all kinds of companies. For example, one of the builds we brought to SHOT Show was a KRG Chassis, Falkor Defense action, Thunder Beast suppressor, and one of our barrels.

What are you thinking for MSRP?

Still figuring out what our final MSRP will be, but our rough ballpark for these barrels will be $225-350 price range, depending on length.

Ok, we have to ask… what about the barrel life?

We can’t confirm just yet the barrel life on these, as they’re still really new. We’re currently mid-testing one and have gotten up to 1000 rounds through it.

What barrel contours will be available?

AR10 barrels will be a modified big gunner profile. Remington 700 barrels will be a modified light palma profile.

What will the gas length be on the AR10 barrels?

8 and 10 pistol length, 16 carbine length.


Now…curious what the 5.7 is all about

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1 Comment

  1. Paul

    What’s your ideal partnership with an ammo sponsor look like? Are you opposed?

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