8.6 Blackout accuracy and barrel twist

[45-90]

So millions of plains Buffalo were killed with subsonic heavy bullets by the time of impact with old black powder rifles, in slow twist barrels from 1-20 to 1-48 twist. Custer killed game to feed the 7th calvary with his favorite 50-70 1-48 twist with around 450 grs. of bullet he claimed out to 600 yds. 44-40 rifles and 45 Colt revolver were ride up and shoot em Buffalo killers. The Majority of the Buffalo had been killed before the Sharps rifles were brought into play with their longer range capabilities. So a slow twist black powder rifle is responsible for wiping out the majority of the Buffalo herds, elk, deer, wolves, & bear, in North America...T Roosevelt introduced conservation, and Yellowstone National Park to preserve the last remaining Buffalo in N America. Custer would prefer his 50-70 as did many hide hunters of the period the 1-48 twist killed millions of Buffalo. Didn't need no 3 twist to get the job done. Fact is...That's a pretty good outdoor laboratory the demise of all the game herds of N America, 10 of millions of animals killed, not to mention all the thousands of people killed, revolutionary War, Civil War, Indian Wars, etc with slow twist black powder weapons all...So, a faster than necessary twist is already proven unnecessary. All ya need is a stable bullet or ball, and the forward velocity does the rest...fact ...end of story.
But you're welcome to twist away, and shout about how good it is..."twist & shout". For ye old fans of the long haired creeps from England.

 

[45-90]

The claims of 1:3 delivering more energy still don’t make a lot of sense to me. A given load of powder has X amount of energy it can impart to the bullet. Any additional energy put into rotation is energy that wasn’t put to forward velocity, and they will offset by probably the exactly identical amount.

Now that is logical scientific thinking...I like that...X amount of energy used imparts the same amount in output, since energy can not be created or destroyed...but transfered... when a little more powder is added the result will still be the same...equal.
Energy in, energy out is equal...what is lost to rotational will be added to forward if heat energy transfer is equal...Physics.

 

[newguy2k3v2]

The more I think about it, the more it seems like it can or will help bullet expansion, which, more expansion equals more energy delivered to tissue before exit. Given the same hydraulic force causing the bullet to expand, it seems reasonable that a bullet that’s closer to spinning itself apart due to rpm would expand more and/or faster than one spinning slower.

 

[PappyM3]

Now that is logical scientific thinking...I like that...X amount of energy used imparts the same amount in output, since energy can not be created or destroyed...but transfered... when a little more powder is added the result will still be the same...equal.
Energy in, energy out is equal...what is lost to rotational will be added to forward if heat energy transfer is equal...Physics.

Except the bolded part is not true when you have a velocity limit with subsonics. When velocity is limited, you could theoretically add more energy by spinning it faster. I mentioned that in my reply to him. But I did also mention that any additional energy would be very small and not relevant other than the rotational energy bleeds off at a much slower rate over range than the traditional kinetic energy based on velocity and mass. But still, it’s such a small amount that it’s conservation still doesn’t mean much.

Ultimately, the rotational energy on target doesn’t mean much of anything. That said, the rotation could affect how the overall energy is transferred and how the tissue reacts.

The more I think about it, the more it seems like it can or will help bullet expansion, which, more expansion equals more energy delivered to tissue before exit. Given the same hydraulic force causing the bullet to expand, it seems reasonable that a bullet that’s closer to spinning itself apart due to rpm would expand more and/or faster than one spinning slower.

True, but you’d need to design a bullet to take advantage of it.

 

[ShadowAviator]

From the video I have seen, the 3 twist does seem to help the projectile expand and thus dump its energy sooner.

However this also caused a smaller cavity as the bullet penetrated deeper.

I think this could be accomplished with bullet design instead of twist rate which has drawbacks.

I don't hate the idea of using a fast twist to change bullet performance, but I feel there are other ways to do that.

Additionally, can a 8.6 be chambered in a 308 chamber? It looks like it could if you used the right (or wrong) bullet in the 8.6.

 

[PappyM3]

So millions of plains Buffalo were killed with subsonic heavy bullets by the time of impact with old black powder rifles, in slow twist barrels from 1-20 to 1-48 twist. …..So, a faster than necessary twist is already proven unnecessary. All ya need is a stable bullet or ball, and the forward velocity does the rest...fact ...end of story.
…

We, as a species, have also hunted animals to extinction with bows and spears. That doesn’t prove that firearms are unnecessary. It doesn’t prove anything about future technological advancements. Old 19th century firearms killing things doesn’t prove anything about modern technology.

I’m not even advocating for 1:3 twist. Just that potential benefits are not “settled science”, which you seem to imply.

 

[45-90]

It is absolutely true that given equal powder charge on the two twist rates 3 and 6.5 with the exact same bullet...the energy transfer is Equal, what is not used in rotational energy will be used in forward velocity. Hence equal.
Can not change physics ...but you change the equation by adding more powder to the 3 twist to make up for forward velocity of the 6.5 twist making your energy input more. Or unequal.
This is really a moot point as different barrels and variations in chamber, plus shot to shot velocity variations are more than the energy delivered by rotational velocity. It just isn't there.
One tenth or 2 tenths of powder added to make up the unequal energy difference is of no consequence...
Since the bullet doesn't sit in one spot & spin or even spin its way through, it can not add much.
The bullet only turns once every 3 inches of advance it only doubles the turns of a 6 twist through the medium. Say a 12" thick target the difference is 4 turns vs 2 turns. Hardly a killer spinning effect. Plus the fact the bullet can stop spinning at any time, or even tumble end over end, as seen many times.
Extra spinning could help a bullet open, but that is dependent on many factors like bullet construction and velocity. But low sub velocity changes things, like force and energy need, and why all the bullets are hollowed and segmented.
Quick expansion looses energy so a bullet can not penetrate as deep...there is a finite amount of energy in the moving bullet. If it fragments or looses petals all these things contribute to the wound or lack of wounding and penetration...
So many variations the same bullet doesn't act the same or kill the same every time, with the same twist and powder energy input. In a live animal the tissue will not react the same every time, tougher arteries, tendons, mussels.
So, bottom line I have given up on the 3 twist in favor of the 6.5 twist for my needs as I find the Faxon 3 twist all negative and no positive.
You folks like it, you keep it.

 

[ShadowAviator]

In a live animal the tissue will not react the same every time, tougher arteries, tendons, mussels.

I don't think you need an 8.6 for mussels.

You just go out in the ocean and grab them.



My stupid jokes aside, I agree, I think the slower twist would be the way I would go, if I wanted less headaches.

 

[45-90]

I don't think you need an 8.6 for mussels.

You just go out in the ocean and grab them.



My stupid jokes aside, I agree, I think the slower twist would be the way I would go, if I wanted less headaches.

Yep, I agree muscles...and mussels aren't the same...and probably don't have the same energy input/ output...or twist rate if applicable?
My mind was spinning, my vision turning, and fuzzy, from my fast spin, as I spun around like a gunfighter, with my fast twist 8.6 rifle, hunting on the coast...near the ocean, on the beach, when an elk walked out of the brush, after penetrating the elk muscles, the fast twist barrel and buzzsaw bullet allowed me to also harvest a few mussels for a complete surf & truf meal.... spinning a tale...or tail. Wagging the dog. The 3 twist will get you spinning, including unwanted extra spind drift, at longer ranges. Put it on a drift calculator. Keep your imagination spinning, but in the real world the 3 twist ain't practical, let alone beneficial in any meaningful or consistently measurable way to justify it's existence, as many are trying to do, ..."it could," or "it might" or " under microscopic examination" etc. But it has alot of limiting draw backs, that do not outweigh even smallest measurable improvement, if it could be found and consistently repeated. I wouldn't dump my 3 twist, for a 6.5 twist, if it was any good.

 

[JDBhunting365]

 

[JDBhunting365]

https://m.facebook.com/groups/761450699011112/?ref=share&mibextid=S66gvF

 

[PappyM3]

This is only one sided data, without a compatible shot from a slower twist. But I do have to say this subsonic expanding solid from a 1:3 twist created a fantastic permanent wound cavity here. It definitely turned temporary cavity into permanent and didn’t just use crush/laceration. It’s atypical for subsonic bullets to turn temporary cavity into permanent.

 

[JDBhunting365]

https://m.facebook.com/groups/761450699011112/?ref=share&mibextid=S66gvF

10 inch 1:6.5 twist
Maker Rex 300gr 338
Spectre damage on whitetail deer

 

[JDBhunting365]

 

[PappyM3]

https://m.facebook.com/groups/761450699011112/?ref=share&mibextid=S66gvF

10 inch 1:6.5 twist
Maker Rex 300gr 338
Spectre damage on whitetail deer

I don’t have Facebook. But I’ll assume it is an example of wounding from a 1:6.5 twist 300gr expanding solid? Able to download and repost the picture(s)?

338 razorback and spectre seem like really solid options for people who only want subsonic capability. I’d argue better options for that given the weight and size savings for cartridges and platforms. I would personally be happy to see 8.6blk flounder with factory support and see one of those two get picked up more.

 

[JDBhunting365]

I don’t have Facebook. But I’ll assume it is an example of wounding from a 1:6.5 twist 300gr expanding solid? Able to download and repost the picture(s)?

338 razorback and spectre seem like really solid options for people who only want subsonic capability. I’d argue better options for that given the weight and size savings for cartridges and platforms. I would personally be happy to see 8.6blk flounder with factory support and see one of those two get picked up more.

 

[PappyM3]

View attachment 8290708

Thanks. I see a big exit wound, but can’t tell if the other tissue damage is from crush along the path of the bullet or if elastic limits of tissue along the way were surpassed.

 

[Jeremiah Johnson]

I bought an 8.6 barrel from Mos-Tek in 1/3 twist for my Terminus Zeus QC action. I am getting MOA groups at 100 yards with Gorilla 285 Subs. Velocities averaged 1050fps. This bullet obviously is not for everyone. It is so far a perfect subsonic hunting bullet for me. I want to try their 342 Grain bullets next

I am going to be using it for night time hog hunting mostly in the city limits. I plan on SBRing and cutting the barrel down to 9" that is the shortest i can do on the MPA ultralight with my suppressor. Currently using a 9mm Dead Air wolfman. It is very quiet. I ordered a Diligent DTFT 338 suppressor for it a couple months ago. Hopefully I will get it by summer

 

[ShadowAviator]

I bought an 8.6 barrel from Mos-Tek in 1/3 twist for my Terminus Zeus QC action. I am getting MOA groups at 100 yards with Gorilla 285 Subs. Velocities averaged 1050fps. This bullet obviously is not for everyone. It is so far a perfect subsonic hunting bullet for me. I want to try their 342 Grain bullets next

I am going to be using it for night time hog hunting mostly in the city limits. I plan on SBRing and cutting the barrel down to 9" that is the shortest i can do on the MPA ultralight with my suppressor. Currently using a 9mm Dead Air wolfman. It is very quiet. I ordered a Diligent DTFT 338 suppressor for it a couple months ago. Hopefully I will get it by summer
View attachment 8297332

Nice setup!

Mos-Tek seems to be the way to go. I have heard good things about their 8.6 barrels of any twist and they did a beautiful job on my raptor barrel.

 

[Jeremiah Johnson]

Nice setup!

Mos-Tek seems to be the way to go. I have heard good things about their 8.6 barrels of any twist and they did a beautiful job on my raptor barrel.

View attachment 8297341

Nice. I was curious about their CF barrels. Looks nice

 

[Zback]

Finally shot some Gorilla 210gr TSXs after their 285s grouped (or didn’t group at all) terribly. They was 2-3 MOA at 100, still less than ideal, but good enough to kill this at 19yds

 

[hlee]

Finally shit some Gorilla 210gr TSXs after their 285s grouped (or didn’t group at all) terribly. They was 2-3 MOA at 100, still less than ideal, but good enough to kill this at 19ydsView attachment 8299659

Good thing you got him. Poor guy was going to starve with that stick wedging his mouth open.

 

[Zback]

Good thing you got him. Poor guy was going to starve with that stick wedging his mouth open.

Put him out of his misery lol

 

[puddleglum]

I'm not going to get in design of the bullet but lets look a 338 match bullet that is 1.8" long. At 1100fps that only needs a 1-8.45 twist minimum. If the bullet is 2" long in 338 cal at 1100fps that only needs a min of a 1-7.943 twist.

Using this example, a 1:7 twist would stabilize these bullets. In your opinion, would a 1:6.5 or 1:6 twist make them more stable, or is stable just that: stable?

Guys.... as you approach 300k bullet rpm and I'll say the hard line in the sand is 300k. Bullet failure is going to be a problem.

At 1400fps out of a 3 twist barrel that gives you 336k rpm on the bullet.

With a 3 twist barrel you will have to limit your velocities to 1200fps or less. My opinion.

This is very interesting. Running with this, I did a little math and it looks like, with a 1:7 twist, velocities should stay at 2900fps or less and, with a 1:6, they stay at or under 2500fps, if using non mono-copper bullets.

 

[Frank Green]

Using this example, a 1:7 twist would stabilize these bullets. In your opinion, would a 1:6.5 or 1:6 twist make them more stable, or is stable just that: stable?



This is very interesting. Running with this, I did a little math and it looks like, with a 1:7 twist, velocities should stay at 2900fps or less and, with a 1:6, they stay at or under 2500fps, if using non mono-copper bullets.

For the most part... stable is stable. Sometimes the bullet design is an issue...and spinning it faster might help it some but it is only hiding a problem that is still there.

Also if the bullet has any runout or your loaded ammo has excessive runout a faster twist can amplify the situation and cause accuracy issues as well. So again.... spinning it faster isn't a cure-all.

You are correct on the second part.

 

[puddleglum]

For the most part... stable is stable. Sometimes the bullet design is an issue...and spinning it faster might help it some but it is only hiding a problem that is still there.

Also if the bullet has any runout or your loaded ammo has excessive runout a faster twist can amplify the situation and cause accuracy issues as well. So again.... spinning it faster isn't a cure-all.

You are correct on the second part.

Thank you.

Do you think bonded bullets will hold up better than softer cup and core bullets, or will the softer bullets be likely to fail sooner than 300K rpm?

 

[Frank Green]

Thank you.

Do you think bonded bullets will hold up better than softer cup and core bullets, or will the softer bullets be likely to fail sooner than 300K rpm?

If I had to guess they will hold up but... your still probably going to deal with overspinning and accuracy issues.

 

[Kyshooter94]

What are the thoughts on running a 1/9 twist barrel for the 8.6BO?

 

[Frank Green]

What are the thoughts on running a 1/9 twist barrel for the 8.6BO?

What bullet (length of bullet) and what velocity? That's where you have to start.

So far every bullet I've looked at and measured.... at subsonic velocities.... I don't see a need for anything faster than a 1-7 twist.

 

[Kyshooter94]

Looking to shoot subsonic from a bolt action. Likely 225gr bullets around 1100fps with a 16" barrel

 

[biffj]

With that bullet weight unless you're talking round nose I think I'd lean toward 1-8. That is going to be a pretty long bullet and that means faster twist for stability. You may get away with 1-9 but its going to be iffy....

Frank

 

[Frank Green]

Looking to shoot subsonic from a bolt action. Likely 225gr bullets around 1100fps with a 16" barrel

I really need the bullet overall length.

But I'll say a 1-9 twist or a 8 twist should be plenty fast for what your telling me. I don't have any 225's laying around to measure for ya.

 

[DRWilson]

I have been trouble shooting, what I thought was a bad Faxon barrel out of my bolt gun. It was the suppressor. We isolated the ammo; ammo was fine. We isolated the barrel; shot great without the suppressor. Then isolated the suppressor, it was causing some wicked yawing of the bullet out of the can. Company has the suppressor and are troubleshooting.

 

[tom12.7]

How well did it group without the suppressor?

 

[DRWilson]

How well did it group without the suppressor?

1.1MOA with a 5 shot group w/o suppressor. With the CGS Hekate, it was too big to count… maybe 15-20moa. Both I and gorilla repeated those same results. I have shot another Hekate on a 6.5 cm and it was no problem. And I have seen on YouTube, the Hekate used for 8.6blk and it appeared to be fine. It’s getting sorted out right now.

 

[Blaster7Romeo]

Any updates on SAAMI acceptance? sence Hornaday pulled the backing

 

[AMMOWASTER]

Any updates on SAAMI acceptance? sence Hornaday pulled the backing

When did Hornady do that? Got any more info?

 

[45-90]

I have the 8.6 Blackout in both the 3 twist purchased early with all its faults and a 6.5 twist purchased much later after being dissatisfied with the horrible Faxon 3 twist.

A world of difference in accuracy and compatability with all bullets.
Excellent accuracy and high velocity with cheap lead bullets.
200 gr cheap lead bullets at almost 2600 fps
Or 225 gr sp bt hunting bullets a over 2400 fps...
300 gr SMK with 1680 subs shot low in the tape 8 shots, into a nice ragged hole.
Or 160 gr Barnes at 2800 fps.
The change from AR 10 Faxon 3 twist upper, to Rem 700 McGowen barreled 6.5 twist bolt gun is unreal.
All problems absolutely totally eliminated.
The 3 twist was unworkable for me no velocity, no accuracy, way too limited on what one could do with it
But I didn't give up on the 8.6 Blackout, I saw what the problem was, the torn, smeared, crappy rifling of the Faxon barrel. And that the 3 twist was a mistake...at least in terms of accuracy and usability...and for my needs.
These supers can run with much larger cartridges like the 308 or 30-06 in factory loads for some real killing power in the field.
This was my journey with the 8.6 Blackout, from a destructive but limited device to a cartridge with merit.

 

[Blaster7Romeo]

When did Hornady do that? Got any more info?

Back at Shot show IIRC.. Keven B put it up on his IG and google lead me here https://texags.com/forums/34/topics/3441049/1 and also a youtube video

 

[AMMOWASTER]

Back at Shot show IIRC.. Keven B put it up on his IG and google lead me here https://texags.com/forums/34/topics/3441049/1 and also a youtube video

That video sure doesn't seem to have any real info. I have no idea who he is but that was all conjecture so I guess we will have to wait and see. I hope Hornady didn't drop it all together because they are good at supporting weird stuff. The more successful this is the better the chances that we get more Blackout and similar rounds.

 

[Blaster7Romeo]

Keven B. the owner of Q said it himself on his Instagram... I consider him a reliable sorce, on this matter..

 

[PappyM3]

Keven B. the owner of Q said it himself on his Instagram... I consider him a reliable sorce

Are we thinking of the same Brittingham?

 

[tom12.7]

After the last meeting I asked Alan Serven about the status of 8.6 Blackout. He said it wasn't under consideration, there's no action pending on standardization. Hornady was tight lipped about it, but there was grumblings about a preference to a slower 1 in 5" to 1 in 6.5" twist.

 

[Blaster7Romeo]

Are we thinking of the same Brittingham?

well I know some people do not like him. I get that..
BUT. When it comes to the latest info on a round that is company is jointly developing I would assume that he would have the most current info.

it is also a couple of mounths after SHOT show and it is still not approved buy Saami so there is also that

I don't want this to go in to a Keven bashing thread I was just looking to see if anyone had heard anything else about what the hold up is.

 

[45-90]

After the last meeting I asked Alan Serven about the status of 8.6 Blackout. He said it wasn't under consideration, there's no action pending on standardization. Hornady was tight lipped about it, but there was grumblings about a preference to a slower 1 in 5" to 1 in 6.5" twist.

I spent a bunch of time on the 3 twist and find it a total dog... IMO, not accurate, limited velocity, especially with lead bullets, anything above 1200 fps can be dangerous, with mostly use expensive copper bullets best option with muzzzle devices.
Went to 6.5 twist with my own reamer and a whole new world of high velocity and accuracy is open to you.
No manufacturer in his right mind would chamber this cartridge in a 3 twist..it ridiculous and not needed or desired.
Hornady will use a slower twist like a 6, with a different case to override the 3 twist problems, if they chamber something it will not be interchangeable with the 8.6 Blackout.
The 8.6 Blackout case has a bit too much volume for subs only and not a lot for supers....but its pretty good with a quality 6.5 twist, and lead supers are close to 338 Federal factory loads in longer barrels and more accurate with the 300 gr subs.

 

[biffj]

Right back to the 338 BR which is pretty ideal in case capacity and overall length. The whole 3 in twist thing was crap from the beginning.

Frank

 

[Yellowjacket1077]

I have a buddy that grenaded a suppressor with a 270 ELD-X. Way to take a bullet that's viable for .338 Lapua mag big game hunting and make it disintegrate in flight.

Also, as for the OP, every bullet has eccentric mass. That can be from manufacturing (jacket/core runout, machining runout, dents, dings,etc..) or from the firing event (uneven engraving, principal axis tilt, feeding damage, scraping, etc.)... Regardless, more rotational velocity causes that eccentric mass to have more outward force and more dispersion. So it's not surprising to me to hear that stupid fast twists are causing erratic dispersion... Not the first time that has been noted.

It could be why benchrest Shooters use as little twist as possible.

 

[WindstormSCR]

I've come around to the reasoning behind the dimensions of the case and cartridge (using unmodified polymer 308 mags with guide rails) but the 1:3 twist is still something I wouldn't touch. If I build or buy one it'll be in a more reasonable twist that doesn't have a chance of exploding my suppressors.

 

[45-90]

Another caliber to consider is the 510 Whisper, pictured here with a 750 Amax along side a 8.6 Blackout with a 350gr Maker.
They also make a 750 gr sub bullet for the 510.
The 510 Whisper is versatile, low velocity subs or lighter supers were putting out 4700 ft/ lbs of energy on the first bullet/ powder combo tried.
Just got the 510 put together, as I spent alot of time getting the 8.6 to shoot up to my expectations, which took a barrel change to 6.5 twist and get away from the 3 twist.
No twist issues with the 510 Whisper it has a 10 twist, normal for 50BMG is 15 twist.

 

[AKPoaster]

I recently picked up a 8.6 BLK barrel from Ballistic Advantage. It's a 1:3 twist. I have only the barrel thus far for an AR10 build, but I'm scouring forums of anyone who has gotten into 8.6 to see if there's reliable beta. @45-90 you seem to have the most informed and strongest opinion against the 1:3 twist in concept, and Faxon specifically at least in regards to the barrel you received from them. @Frank Green you come with industry insight and on this topic which is highly valuable.

My own take comes from listening to the developers of the cartridge and their respective firearms. Yes they are all selling something, but logically it would make no sense to throw this much investment at a physics fail. Sure you'll get early adopters and acolytes, but that's not what'll get them the ROI...they'll need the normies for that. Q blatantly doesn't market to the poors, and has openly been critical of other companies trying to break onto the 8.6 scene before they've even worked out all the kinks themselves. I recall a video featuring Kevin where he specifically lambasted the 1:6.5 twist as basically the best the rest of the industry can accomplish without upgrading their tooling, or something to that effect.

Really what this cartridge boils down to is a pet project that has gone somewhat viral. In any cutting-edge development, you're going to have extensive T&E. Time will tell if the 1:3 really is THE ideal twist rate for 8.6 or if something slower is going to be more widely accepted. Kevin has spoken about going as low as 1:1! They're manipulating all the variables (bullet weight, powder charge, bullet composition/shape, barrel length, muzzle device, etc.) which seem to be trending towards something very niche: high penetration, subsonic performance out of 8-12" barrels. In my listening, this was the rationale for arriving at 1:3. But is this what customers will want or even find useful/worth their money?

Time will tell