The 8.6 Blackout: Specs, Ballistics and Origins

The 8.6 Blackout is a .338 caliber rifle cartridge that SAAMI identifies as 8.6 BLACKOUT, abbreviated 8.6 BLK. SAAMI announced its acceptance for standardization on January 29, 2026, names Q, LLC as the introducer, and lists a 62,000 psi maximum average pressure.

What 8.6 Blackout is

8.6 Blackout is the SAAMI-standard name for the cartridge commonly discussed as 8.6 BLK. Although the metric shorthand 8.6x43mm is often used, SAAMI’s listed cartridge name is 8.6 BLACKOUT.

In practical terms, it is a .338 groove diameter cartridge designed for the .308-size rifle world. Faxon says 8.6 BLK fits a standard .308 magazine, which is why it draws attention from AR-10 and other .308-pattern rifle shooters.

SAAMI lists a .330 inch bore diameter and .338 inch groove diameter.

Origins and the .300 Blackout connection

SAAMI says 8.6 BLACKOUT was introduced by Q, LLC. Faxon also states that Q developed 8.6 Blackout and that Faxon worked with Q on 8.6 BLK barrels.

Faxon describes 8.6 Blackout as the “big brother” of .300 Blackout. That comparison is useful because both cartridges are commonly discussed in subsonic and supersonic terms, and both are associated with short rifle formats.

The development story for 8.6 BLK points to Q. Shot Business quotes Q’s Cody Osborn saying Q launched 8.6 BLK into the commercial market in 2023. The same article quotes Osborn saying that, after 300 BLK at AAC, Kevin Brittingham and Ethan Lessard set out on what became 8.6 BLK.

Shooting Illustrated says Kevin Brittingham worked at SIG Sauer for a short time before starting Q. Q is identified as the introducer, with SIG Sauer relevant mainly to Brittingham’s employment history.

SAAMI status and published specifications

SAAMI announced acceptance of 8.6 BLACKOUT for standardization on January 29, 2026.

Specification	SAAMI listing
Official cartridge name	8.6 BLACKOUT
Abbreviated name	8.6 BLK
Introducer	Q, LLC
Maximum average pressure	62,000 psi
Instrumental velocity	200 grain bullet at 2,200 fps
Bore diameter	.330 inch
Groove diameter	.338 inch
Velocity and pressure test barrel	16 inches
Test barrel twist noted by SAAMI	6.00 inch right hand optional

SAAMI states that crusher pressure limits were not established for 8.6 BLACKOUT. SAAMI also lists Q, LLC as the support products supplier for the 8.6 BLACKOUT reference, dummy, and proof ammunition package, with Q86BLK as the reference round order symbol.

The twist information is worth reading carefully. SAAMI’s drawing notes six grooves and an optional 6 inch right hand twist, while Faxon and other industry coverage discuss commercial 8.6 BLK barrels with a much faster 1:3 twist. Those are not the same thing. SAAMI’s drawing gives the standardized reference dimensions, while the commercial 1:3 twist barrels are part of how the cartridge has been marketed and built for many early rifles.

Parent case and rifle fit

Faxon describes 8.6 BLK as using a shortened 6.5 Creedmoor case for subsonic and high ballistic coefficient .338 projectiles. Faxon also says it will fit in a standard .308 magazine.

That combination explains much of the cartridge’s appeal to .308-size AR shooters. It gives the shooter a larger .338 diameter projectile while retaining the magazine fit described by Faxon. It is not simply a larger .300 Blackout, but the comparison helps new readers understand the idea: a cartridge family concept with subsonic and supersonic loads, short rifle interest, and a focus on heavier bullets than many small-frame AR cartridges.

Published load examples and ballistics

SAAMI’s baseline velocity entry is a 200 grain bullet at 2,200 fps. That gives a standardized reference point, but early commercial and industry information covers both heavier subsonic loads and lighter supersonic loads.

Gorilla’s published 8.6 Blackout data sheets identify several Punisher Series projectiles. Its 342 grain Punisher Series Expanding data sheet identifies the load as an 8.6 Blackout subsonic expanding projectile and lists a 12 inch test barrel, with velocities from 985 to 1,025 fps depending on powder. Its 285 grain Punisher Series Fracturing data sheet identifies an 8.6 Blackout subsonic fracturing projectile and lists a 12 inch test barrel, with a 1,050 fps velocity for one maximum entry.

Shooting Illustrated reports Gorilla factory 8.6 BLK offerings that include a 210 grain Barnes TSX at 1,925 fps and a 300 grain Sierra MatchKing at 1,050 fps. Shooting Illustrated says those advertised velocities are from a 12 inch barrel with a 1:3 inch twist.

Load or reference	Bullet weight	Published velocity	Barrel information
SAAMI instrumental velocity	200 grain	2,200 fps	16 inch velocity and pressure test barrel
Gorilla Punisher Expanding subsonic	342 grain	985 to 1,025 fps	12 inch test barrel
Gorilla Punisher Fracturing subsonic	285 grain	1,050 fps listed for one maximum entry	12 inch test barrel
Gorilla factory offering reported by Shooting Illustrated	210 grain Barnes TSX	1,925 fps	12 inch, 1:3 twist barrel
Gorilla factory offering reported by Shooting Illustrated	300 grain Sierra MatchKing	1,050 fps	12 inch, 1:3 twist barrel

These figures should not be treated as interchangeable. Barrel length, chamber, ammunition lot, bullet construction, and test method can all affect published velocity. The important pattern is that published 8.6 BLK information includes both heavy subsonic loads in the 285 to 342 grain range and a lighter supersonic example around 210 grains.

Fast twist barrels and terminal-performance claims

A major part of the 8.6 BLK story is twist rate. Faxon says Q developed the cartridge around a faster 1:3 twist rate, compared with common 1:7 and 1:8 twist rates for cartridges such as 5.56 NATO and 300 BLK.

Faxon’s 2022 8.6 BLK barrel plan included 8 inch, 12 inch, and 16 inch AR-10 barrels, all with 1:3 twist. It also included 8 inch, 12 inch, and 16 inch Remington 700 platform barrels, also with 1:3 twist.

Shot Business quotes Q’s Cody Osborn saying that increasing twist rate was part of Q’s development work for accuracy and terminal performance. The same article frames that development around keeping the system short and light, with 8.6 BLK entering the commercial market in 2023.

For hunters, that means the cartridge is best understood as a short rifle, heavy bullet concept with both subsonic and supersonic load paths. Shooting Illustrated describes Q’s goal for 8.6 BLK as better terminal performance and more reach than .300 BLK at subsonic and supersonic velocities.

Where it fits for hunters and .308-size AR shooters

8.6 BLK is not a general replacement for every .308-size cartridge. Its published identity is more specific: .338 diameter bullets, a shortened 6.5 Creedmoor case as described by Faxon.308 magazine compatibility as described by Faxon, and a fast-twist barrel ecosystem built around short rifle formats.

The cartridge will naturally interest hunters who are already looking at heavy bullets, short rifles, and subsonic or supersonic options. It will also interest AR-10 shooters because Faxon says it fits a standard .308 magazine and listed 8, 12, and 16 inch AR-10 barrels in its 2022 8.6 BLK plan.

It is closely related to the .300 Blackout conversation, but it is not the same cartridge scaled up in every detail. The 8.6 BLK examples above include much heavier .338 diameter bullets, such as Gorilla’s 285 and 342 grain subsonic projectiles, and a supersonic example around 210 grains.

What to verify before buying or hunting with 8.6 BLK

Use SAAMI’s 8.6 BLACKOUT drawing for the standardized cartridge name, pressure, dimensions, and test barrel reference. Use current ammunition maker data for velocity and barrel length, because the published examples vary by bullet weight and test setup.

Hunters should also check current state or provincial hunting regulations before using 8.6 BLK on game. Confirm cartridge, bullet, magazine, suppressor, barrel length, and method-of-take rules with the wildlife agency for the exact place and season you plan to hunt.