8.6 BLK rifle cartridge

[Kurz]

8.6 Creedmoor or 8.6 BLK or 8.6 Blackout?​

November 18, 2021 by AJ 8 Comments

8.6 BLK next to a 300 BLK (image from Facebook)

What is a 8.6 Creedmoor?​

First off, it is now officially called the 8.6 BLK or 8.6 Blackout, dubbed such by the very creator Kevin Brittingham. Kevin, owner of Q and inventor of the .300 Blackout cartridge first came up the with idea of a .338 caliber cartridge like the .338 Federal, but better because it has a shorter 6.5 Creedmoor based case, so it could accommodate larger and longer bullets than the .338 Federal in normal magazines, which would mean it could provide for a cartridge that could be effective at both subsonic and supersonic muzzle velocities. Not only does this owe for interesting low-noise subsonic rifles, but also for short barrel, high-punch rifles and even a cartridge being able to feed in a semi-auto configuration.

Back in 2018 when Kevin initially developed the cartridge and worked with the idea, trying to get Hornady to start manufacturing the cartridge, he intended to call it the 8.6 Creedmoor, but in June 2021 when Q made the official announcement of the cartridge on their Instagram account, they dubbed it the more appropriate 8.6 BLK or 8.6 Blackout, owing to their own unique .300 Blackout, but necked up to accommodate the 8.6 caliber bullet, and also uniquely identifying it as separate from the Creedmoor sports developed cartridges like the 6.5mm Creedmoor and the 6mm Creedmoor.

The reason why Q and Hornady are only now officially bringing it to market in 2021, is mainly because of the ammo crisis that hit since early 2019, which meant that they could not even keep up with demand of current cartridge ammo, let alone start manufacturing or marketing a new cartridge.

Brass​

Initially to create brass for 8.6 BLK cartridges, one could cut shorter and neck down high quality 6.5mm Creedmoor brass with a good full length sizing die and enough case lube. Thankfully though, if you are a litle patient, both Q and Hornady, should have brass available soon.

A rare and elusive 8.6 BLK case, Image from Facebook

Why a New Cartridge​

Yes, it feels like every week someone is just necking some other cartridge up or down and “bringing out a whole new cartridge”, but this time, it is really a game-changer. The 8.6 BLK is not just an improvement on previous designs or a wildcat, it changes what was thought best for hunting cartridges and tactical military cartridges all together. It shows that large long bullets can work out of small cases, and even better, high energy effective hunt kills can be made out of short barrels, even at what would be considered long range distances for hunting.

Create Your Own​

There aren’t really any large scale manufacturers making a 8.6 BLK Factory Rifle yet, however, if you jump on the waiting list now, you may be able to snag one of the early ones when they become available soon from Q, or you can even just buy a barrel conversion from them if you already have a Fix by Q.

The other manufacturers should jump on the band wagon offering 8.6 BLK chambered barrel pretty soon after Hornady starts making the brass available, and you can even have your own build on a .308 bolt face, standard-length action, by chambering a .338 / 8.6mm barrel in it once reamers become available (just remember the tight twist rate needed to make the most of this cartridge).

8.6 BLK Twist Rate​

Very fast twist rates like 1:4 and even 1:3 are used for the 8.6 BLK, as this provides greater energy at supersonic velocities, and greater accuracy at subsonic velocities, thus enabling the use and stabilization of such long and large bullets out of such short barrels. The fast twist rate, also ensures good bullet expansion even at slower velocities.

8.6 BLK Ballistics​

When loaded with a 210gr Barnes TTSX bullet at 2450fps from the short 12.5″ barrel, you only have around 1.4 MOA more drop at an incredible 300 yards than a usual 308 Win with a 168gr bullet would have, but with a whopping 300 ft/lbs more energy on target, and that all from a rifle short enough to fit in your backpack. That is just to show what it can achieve, however we doubt many people would hunt at such long range with it.

8.6 BLK for Hunting​

Although very practical as a new do-all military cartridge, hunting is where the 8.6 BLK really shines. It redefines the general puspose hunting and utility rifle genre. Even during testing and R&D hunts, Kevin Brittingham and the guys from Q have been making waves online with their small Fix 8.6 BLK taking down everything from smaller CXP1 sized animals like a Black Backed Jackal, CXP2 sized game like deer, CXP3 sized animals like a large Kudu bull, all the way through to the very large and thick-skinned CXP4 sized African Cape Buffalo. Proving the versatility of the cartridge and rifle platform for a single, compact, do-it-all hunting rifle.

Yes we know top right is a Fix in 6.5 Creedmoor, but 8.6 BLK will do it to, and the rest are 8.6 BLK (images from Facebook)

8.6 BLK Barrel Length​

Because of the aim of the whole 8.6 BLK development was a compact utility / hunting rifle, it is designed to work well in short, and I mean real short barrel configurations. With Kevin doing most of the 8.6 BLK testing in a 12.5″ barrel, like can be seen in the hunting photos above, they even have a ultra-short and compact 8″ barrel version, still apparently packing more energy at 600 yards, than a .45 ACP round has at the muzzle, unbelievable or in the words of the Q-team themselves, unpossible.

The 8 inch barrel for the 8.6 BLK (image from Facebook)

8.6 BLK vs .338 Federal​

Most people that first read or heard about the 8.6 BLK, quickly asked why, given the similarity or superiority (as they thought) of the already available .338 Federal cartridge. Well, the 8.6 BLK is the quieter and more efficient version of a .338 Federal, basically with a trimmed back case and improved shoulder so you can get longer heavier subsonic bullets than you can with the .338 Federal. Overall it’s a more efficient and versatile design than the .338 Federal.

Whilst the case length of the .338 Federal is 2.015”, the 8.6 BLK case is 1.685” in length, allowing the ability to run heavy subsonic loads, 280 to 360 grains or more, whilst the longer 338 Federal case will put the ogive of those long projectiles back inside the case, which will perform badly.

Although having a smaller case capacity, the 8.6 BLK offers more consistent ignition of the powder, which gives you more consistent performance, especially with those heavy subsonic loads. Another big upside due to the shorter case and cartridge length, the 8.6 BLK will feed out of .308 Winchester length magazines, allowing greater compatibility. Even the fact that the 8.6 BLK uses the same bolt face as the .308 Win, means you can change your barrel on your Fix or other current rifle and have your own 8.6 BLK.

Lastly, when looking a long bullets like the Berger 300gr Hybrid with a nose length of 0.955 inches, but the case to OAL length of the .338 Federal is only 0.785 inches, meaning that those bullest or similar cannot be reliably fed from a magazine, whereas it can in the 8.6 BLK.

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Here is the original link complete with photographs. Beware of idiotic spelling mistakes:

https://www.loaddevelopment.com/8-6-creedmoor-or-8-6-blk-or-8-6-blackout/

Here are a couple of the photos attached to the above article:


8.6 BLK next to the .300 Blackout


8.6 BLK dimension drawing

 

[Forum Boss]

Yes, this is interesting. And actually, there are some new rifles being chambered for the 8.6 Blackout (see Faxon Firearms at 7:16 in video below). This is covered in this video at 4:58, 7:16 and 13:30. They are doing some radical twist rates (1:3") in short-barreled rifles. The goal, as the article explains, to provide stabilty at subsonic speeds, and also to work in very short barrels.

New 8.6 Blackout Cartridge with 1:3″-Twist Barrels

The new 8.6 Blackout “is a 6.5 Creedmoor shortened case, blown out for a .338 bullet [8.6mm = 0.339 caliber]. For supersonic… between 150 and 160 grains. Out of a 12″ barrel, we’ll be able to get somewhere close to 2400 FPS with that. We’ll have subsonic up to about 360 grains. A Barnes 210-grain bullet [is] about 2,000 feet per second out of a 12″ barrel.”– Q’s Kevin Brittingham It is claimed that there is more energy on target than with a .308 Win, even with a very short barrel

The cartridge inventors are running a very radical 1:3″ twist rate. Yep you read that right — one in three. According to Kevin B: “Fast twist … gives you several things. The first being better accuracy because when the bullet is long and slow, you need to spin it faster. For expanding subsonic bullets, it has more reliable expansion at lower velocities, which is great for hunting with subsonic [ammunition]. This is going to be the first subsonic, sub-MOA cartridge, and that’s due to the fast twist.”

 

[Spook]

bears an incredible resemblance to the 338 whisper as I see it?
Mine stabilizes everything I've put through it with an 8 twist.

Ive pretty much switched over to 338 and 375 Grendel, feeds through a "normal" AR like corn through a hungry goose.
AR-ten ...meh if you're young and healthy,why not?

"This is going to be the first subsonic, sub-MOA cartridge, and that’s due to the fast twist.”

Really?

makes you wonder why BR rifles are 14 twist and less?

 

[Kurz]

bears an incredible resemblance to the 338 whisper as I see it?
Mine stabilizes everything I've put through it with an 8 twist.

Yes, but at what range?

makes you wonder why BR rifles are 14 twist and less?

I don't wonder at all. Point blank or 300 yards is the maximum range that your PPC cartridge, bullet weight and twist rate is used for. The 1:14" twist rate is suited to the use of 66 and 68 gr. Match bullets (or whatever you all shoot) in the PPC case.

The cartridge above uses heavy weight, long range, high BC Match bullets at ranges up to and including 1,000 yards. The faster twist rate helps keep these bullets stabilized. The article posted above has all this information.

 

[Spook]

The cartridge above uses heavy weight, long range, high BC Match bullets at ranges up to and including 1,000 yards. The faster twist rate helps keep these bullets stabilized. The article posted above has all this information.

Yes Kurz, we know.
they'll use the same High BC match bullet that everyone is already using, That are being sent to 1000yds plus, very accurately, using considerably less twist than 1:3.

.... while attempting to overcome the variables contained within 1800 inches of drop required to get to 1K at 1050FPS .... by increasing twist?

Given the efficacy of modern suppressors attempting 1k with anything subsonic has become a non starter.
I've messed with 510 whisper enough to know. Velocity is your friend in this arena.

 

[CJ6]

I would like to see what the bore looks like after 20-30 shots with the "high" velocity loads in the 1-3 twist...That has to be a cooper mine.........I also wonder how a normal hunting bullet would stand up to the twist rate.

 

[300_whisper]

I’m all in on this cartridge. I would love to own one…BUT that 1:3 twist concerns me as well. You seem extremely limited using only solids. They can’t slow it down to a 1:5 or 1:6 with similar results?

 

[ebb]

In the second to the last paragraph of Kurz's post the author mentions this cartridge has "more consistent ignition of the powder." More consistent than what cartridge, and why? Most all of the cartridges in that size group use the primers that we have all used for years. Depending on the brass chosen SRP or LRP magnum or standard. Is there a reason he makes this statement, is there something new here that can be used in my standard rifles?

 

[300_whisper]

In the second to the last paragraph of Kurz's post the author mentions this cartridge has "more consistent ignition of the powder." More consistent than what cartridge, and why? Most all of the cartridges in that size group use the primers that we have all used for years. Depending on the brass chosen SRP or LRP magnum or standard. Is there a reason he makes this statement, is there something new here that can be used in my standard rifles?

Not knocking this cartridge, because I really do want one, but I’m sure it’s just marketing hype. Like when all the bullet / cartridge manufacturers publish load data and compare it to some tried and true cartridge. Like in the hunting magazines where they show a simplified graph of a .300 PRC shooting heavy Match grade bullets vs a .300 win mag shooting 150 grain FMJs and comparing downrange performance at a mile. Lol

 

[matthias]

Maybe I am missing something but with that fast of a twist rate won't the bullet act like a boat prop with too much pitch when it hits a fluid ritch target?

Cavitation to a point is good in a hunting round, but where does it hit the point of diminishing returns?

Will the extra twist actually translate to better performance on game?

Or is this just for bullet stability?

 

[300_whisper]

Maybe I am missing something but with that fast of a twist rate won't the bullet act like a boat prop with too much pitch when it hits a fluid ritch target?

Cavitation to a point is good in a hunting round, but where does it hit the point of diminishing returns?

Will the extra twist actually translate to better performance on game?

Or is this just for bullet stability?

Its both. The creators have used it on Cape buffalo with success.

 

[CJ6]

Its both. The creators have used it on Cape buffalo with success.

Elephant have been taken with 7 x 57 Mauser too..It doesn't mean it's the proper round for them.

 

[300_whisper]

Elephant have been taken with 7 x 57 Mauser too..It doesn't mean it's the proper round for them.

ok lol

 

[matthias]

I am very interested in seeing a side by side comparison of the 1-3 , maybe 1-6 , and like 1-9 twist all other things the same to really validate their claims.

I know that is alot of work but it would go a long way to settle some of the concerns voiced.

I am not aware of any other "extreme fast twist" barrels that have a track record to compare.

 

[ebb]

Well I don't see how any marketing hype would be required, its made with Creedmoor brass. Doesn't that mean it has to be accurate? If they had named, it the 8.7 Creedmoor all the marketing hype would have already been bought and paid for.

 

[johnfred1965]

Its both. The creators have used it on Cape buffalo with success.

I've heard of people using 22lr with success on deer, but that doesn't mean it is the right choice. I'm all for innovation, but we already have the whispers and the socoms and the spectres, this seems like the same thing and the fast twist is to differentiate this one in the market.

 

[300_whisper]

Dead’s dead. I never said it was leveling elephants. I’m just saying the creator of this round took it to Africa to prove it can take game…aaaaannndddd he did. He’s got edgy videos of killing stuff all over YouTube.

 

[spencerhenry]

Reminds me of all the long distance hunting shows a few years back. I haven't watched TV in years so maybe they are still there. Lots of animals are shown to be killed at extreme distances, the problem is that, with editing, it looks like it never fails. I knew someone many years ago involved with a long range hunting TV show. He quit due what never made it onto the video for the public.
Just because someone has a video of success, it may not represent reality.

I bought into the 300 blackout hype, I have one that I haven't shot in at least 5 or 6 years.

 

[DangerRanger]

An interesting cartridge, not because I’ll use it but because it’s intended use pushes boundaries and feels specialized and o me

The cartridge is made primarily to be subsonic, yes?
1050fpsx720= 756,000

devide by twist rate to find good rpm range to achieve stability without radically over spinning and destroying jackets. No, I am not stating that rpm is the only factor in bullet stability, I’m saying it is a factor and without adequate rotation it’s not happening. However, adequate twist rate to stabilize a 300 berger at 1050 is like 1:8

A 1:3 twist is sitting them right at 252k rpm range used a lot in long range accuracy competitions. Though, likely faster than we see in short range accuracy competition as noted above. I have to thing they are looking at rpm range a lot with the concept of increasing rotational energy to get around lacking linear energy.

that same 1:3 twist in a supersonic load is going to rip normal jackets to shreds. A 2k fps muzzle velocity in a 3 twist is almost 500k rpm. So we go to solids. As long as people are using factory ammo, and factories don’t make stupid choices we shouldn’t see failures and poofs, but gosh 500k rpm is spinning.

i have been interested for some time in the effect of rotational energy on game. It *seems* from talking to some people increased twist not only increases trauma seen on target but also reduced the chance of a bullet deflecting off line in soft body. I don’t believe that has been tested in a controlled manner but I’ve seen mono bullet makers entirely change(speed up) recommended twist rates based on it.

hunting is a weird part of shooting, it makes us meld the most accurate system possible with the most effective system possible. We all have preferences and ideas on what combination gives us the promise land, but it’s fun to think and experiment and maybe sometimes we find other neat things that work and sometimes well.

this is me looking past marketing tag lines or anything Kevin says or does.

 

[Ray123]

I just purchased and fired 130 rounds in the 8.6 blackout....and it's a mixed bag IMO...Here's why, first the Faxon barrel I received was terrible when looked through a bore scope...cleaned it and rust like color and pieces of barrel metal on the patch. Bire scoped it again, the rifling near the chamber was galled rough and jagged with tares and pits in the bore, one across the bore land to land... lapped it with 240 grit silcon carbide, better especially at the muzzle end looks pretty fair.. 3 twist okay for subs only but very limited on higher velocities. I damaged my muzzle break and the Magneto Speed bayonet...and it will definitely damage your suppressor. And it's really a 338 Savage cartridge,...the easiest to make brass out of is the old 300 Savage. I neck turned the rest into the shoulder and Winchester brand commercial 308 is the closest next to the 300 Savage brass.
Today for my purposes I'd trade the barrel out for a 6 twist....the 3 twist is good for subs mostly as I see it. The 3 twist is dangerous when the velocities go into supersonic...of coarse I had to try some supers to find out what was possible. Take off your muzzle devices if you proceed with this endeavor, and be prepared to buy a new Magneto Speed bayonet. The Magneto Speed bayonet can take alot of abuse and still read velocities, mine now has many chunks out of it and looks like crap, and my muzzle break was damaged when the first super sonic bullet came apart measured 1" inside the break it made it through two baffels and come apart in the 3 rd. With out barrel support the bullet comes apart as it exits the muzzle the higher velocity supers were fired at the ground, too dangerous to fire over the chronograph bayonet with a 6 to 10 feet spread of bullet lead and jacket at 10 feet, a wider pattern than any shotgun....exciting. For Subs I used 15 gr of AA1680 across the board of 200, 225, 250, & 285 gr bullets in 16" barrel velocities ranged from 900 to 1100 area...the best load was 250 BT Sierra GK. at 1050 fps wit 15 gr AA 1680 9 shots into .680" with 7.2 S/D at 50 yds. Change to IMR4198 15.9 to 16.1 gr with the 285 eldm, for better accuracy and S/D. Tested at moderate velocities the 285 eldm doesn't make it to the target at 1420 fps in a 3 twist they come apart. The cheap Speer 200 gr will stay together at 1620 fps with good accuracy. So if you run a suppressor stay at 1000 fps or under..."the experts" run at 900 fps with the can on...now I know why.