8.6 Blk reloading info

[Mike6158]

For those looking for a 8.6 Blackout shotgun, ....just load up high velocity lead bullets in the Faxon 3 twist AR 10.
Inside, one could shoot down the hall and cover both walls from ceiling to floor.
Loaded on purpose and fun to shoot.

I like my "quiet time" too much but it sounds like you found a portable frag grenade round.

The best group I got with the Faxon garden stake was 3 shots, 0.449", at 100 yards. N133, 19.5gr. Barnes 280gr LRX. ES-7.9, SD-3.3, Avg velocity 1,135fps. I'd hunt with that if I knew the bullet would perform.

Here's a fine powder load test that's barely supersonic. I worked on it in February of this year and it would be closer to subsonic than it was in February. This is N110. 100 yards. I couldn't find a target. Groups size is in inches and measured with a digital caliper. I have other data for faster loads but either the powder burned dirty or the target data was disappointing, or I had become disillusioned with the idea of shooting supers. Still counting down the days until I get my new barrel.

 

[45-90]

Great! My question was in relation to a 6.5 twist. Thank you for doing so much work!!

Yes the hybrid case runs more powder and gets more velocity without pressure signs and retains tight primer pockets. The advantage is for bolt guns only, as you're on the edge of max AR 10 pressures, and could easily exceed it.

 

[wgranvilleb]

Yes the hybrid case runs more powder and gets more velocity without pressure signs and retains tight primer pockets. The advantage is for bolt guns only, as you're on the edge of max AR 10 pressures, and could easily exceed it.

Any suggestions as to where to purchase some hybrid cases?

 

[45-90]

Any suggestions as to where to purchase some hybrid cases?

There are no hybrid 8.6 blackout cases.

They are made from 6.8X 51 military cases, 277 Fury is the civilian name.
Boxed ammo with hybrid cases are sometimes available at $3 or $4 ea for 277 Fury.

So you have to buy the 6.8X51 cases, and trim them, form them, anneal them, FL size them, turn the necks..
Then you have 80,000 psi to play with, in a strong bolt action.

I do not run these at that level in my 8.6 Blackout, but confine them to 65,000 psi.
Where I have a large safety margin, to experiment with any powder available, and still get good velocity and accuracy.

Never used them in 3 twist, as pressures spike is tremendous in those early horrendous Faxon barrels.


I got the best deal at American Reloading, they had thousands at one time but have been out for quite awhile.

Pictured is the process, of making 6.8X51 to 8.6 blackout. Trimmed, Neck turned, and annealed.
Kind of like cheating to the average guy. Yes, I use real machine tools to accomplish these tasks.
Being a retired machinist with machine tools, turns me into a "mad scientist", altering everything, making dies, chambering rifles, truing actions, making AR barrels from blanks, etc.
Few gunsmiths would do these projects, and would be to expensive to pursue.
But, Not if ya do it yourself.
This can be accomplished within hand tools but more time consuming and difficult. For those who want to pursue this endeavor.
Always learning and improving, share what I've learned which may not be useful to many.
Building another rifle today...a 510 Whisper.

 

[wgranvilleb]

Roger that. . . Thanks.

American Reloading had a hundred so I purchased them and will open another arm of this 8.6 reloading process.

I like the idea of the extra safety margin without any intent of pushing beyond regular levels.

Thanks for the guidance regarding the resizing steps. I purchased the Hornady neck turning machine to get started. By the way, when neck turning, how far do you trim into the shoulder?

Regarding reading pressure with these cases. . .

What signs do you rely on for detecting early increased pressure with these steel based cases?
- Is a "stiff bolt" still a sensitive indicator?
- I'm presuming ejector marks are not as reliable.
- Is the shape / condition of the primer the only sign left?
- What is the thinking for pressure correlation when seeing the primer start to flatten but not fully flattened (and not associated with 'stiff bolt lift).

Sorry for so many questions. Many thanks.

 

[45-90]

Roger that. . . Thanks.

American Reloading had a hundred so I purchased them and will open another arm of this 8.6 process.

I like the idea of the extra safety margin without any intent of pushing beyond regular levels.

Thanks for the guidance regarding the resizing steps. I purchased the Hornady neck turning machine to get started. By the way, when neck turning, how far do you trim into the shoulder?

Regarding reading pressure with these cases. . .

What signs do you rely on for detecting early increased pressure with these steel based cases? Is a "stiff bolt" still a sensitive indicator? I'm presuming ejector marks are not as reliable. Is the shape / condition of the primer the only sign left?

What is the thinking for pressure correlation when seeing the primer start to flatten but not fully flattened (and not associated with 'stiff bolt lift).

Sorry for so many questions. Many thanks.

Here is the dangerous part...you could blow up your action before seeing normal pressure signs.
There will be no pressure signs on the case heads at all.
The only clue is primer extrusion, and your into 80,000 psi.
Stiff bolt lift STOP! You're way over proof loads for your action. Your face next to a grenade.

Stiff bolt lift, you just flexed the action, not even damaging the case necessarily, no marks present on the case head, as you pound the bolt open.


But maybe set back the bolt locking lugs. Need to check headspace before continuing....with a much lighter load.

Do not use in an AR 10 at those pressure levels.

It should be done with some scientific predictive software.

And I don't recommend it for a 3 twist.

Should be applied to slower twists maybe 6 twist on down to really slow, like 22 twist.
Cause the bullet doesn't move out of the way fast enough in a 3 twist to create the correct burn and expanding space in the first few milliseconds, for safe predictive operation...that is what I have experienced.

The 3 twist is really limited to subsonic loads, with low pressures, and velocities where it is mostly safe...and was originally designed for, not fast supers, as I have already experimented with, ...you just can not get there with a 3 twist, it's not what it was designed for.

And why I caution extreme care...

 

[45-90]

So here is a photo of two cases
Left 6.5 CM under 80,000 psi, with 147 gr at 2976 fps.
It would destroy a brass case, and maybe your action, but no visible marks on the case head primer is still not really flat...but the primer is flowing a small teat...your only sign... if the action can take tbe pressure.
Right 8.6 blackout at 65,000 psi...not much difference but full primer radius and slight teat forming around firing pin.
There really are no normal clues, no ejector or extractor marks.
I run the 30° tool into the shoulder when neck turning, to thin the shoulder and eliminate donuts in the neck, anneal and resize.
As one can see there is not much difference in high magnum pressure and 80,000 psi hybrid case max running with these cases.
So it's easy to get into trouble. I shoot them in various calibers, and have more than 1500, plus a bunch of experience with these, as an experimenter and shooter.
My cases are carefully machined so as to fit the chamber freely and release the bullet with out any interference.
One can do the same with hand tools but pay very close attention to detail, so as to keep your face...and I would only recommend the lower 65,000 psi area with QL as a guide for anyone trying this.
It's where I'm running my 8.6 and it's good there.

Many powders do not help past the 65,000 to 70,000 psi area... it gets very limited.
The factory uses a classified, special and specific blend for their loads, in military contracts...not available to handloaders.

Sig has lowered the pressure of their factory hybrid loads to 70,000 psi, they are either 7.5 or 8 twist barrels

Got some machining to do, hope this helps....but be very careful.

 

[wgranvilleb]

@45-90:
Fantastic discussion and demonstration of the pressure signs associated with the hybrid cases.
Thank you for taking the time to write this, and the picture is invaluable.
I have no doubt your information will help as they explore this area of loading.

Many thanks . . .

 

[dnchrist]

Thanks for your comment / suggestion.

Yes, they fit after loading.

Not using reformed cases as of yet, as I wanted to decrease the variables during this early phase of load development.

I have dabbled with reforming some .30-'06 cases, most of it is old Lake City brass. The case walls are thick, and after reforming with neck walls that are > ~ .020". Neck turning these reformed cases with the recently purchased Hornady machine is another challenge with its own learning curve, left for a later time.

I've been having good luck with 6.5 Creedmoor Federal SRP, but they require neck turning.

 

[45-90]

I built a die for roughing 30-06, 270, 308, etc to make 8.6 Blackout.
It will form cases with out case lube, as demonstrated here with this crusty old 270 case. But it's better with a light spray of Hornady lube.
They can be done as fast as you can pull the press handle, no shoulder dents or wrinkles.
Then off to the milling machine to cut to length in about one second, from 270, 30-06, or 308.
Full length size, then to the lathe to neck & shoulder turn.
Works good and brass is free...
By hand there is alot of labor involved...
Mechanize where ever you can.

 

[wgranvilleb]

Awesome . . . looks like quite a time saver.
Any interest in selling one to an interested party in the peanut gallery?

 

[45-90]

Awesome . . . looks like quite a time saver.
Any interest in selling one to an interested party in the peanut gallery?

Doesn't hurt to ask, but no.
Too busy doing other things, plus a lot of guys who form brass would want one of these home build dies.
There are none like it, it's one of my inventions. The idea is probably worth a million bucks.
But maybe RCBS will figure it out... in the meantime, guys will have to use factory built forming dies.

 

[wgranvilleb]

Understood. . . Thanks for considering.

Regarding neck / shoulder turning:
- What is your target neck thickness?
- How far into the shoulder do you turn? Do you just relieve at the neck / shoulder junction or turn the shoulder back to the body?

Thanks.

 

[45-90]

Understood. . . Thanks for considering.

Regarding neck / shoulder turning:
- What is your target neck thickness?
- How far into the shoulder do you turn? Do you just relieve at the neck / shoulder junction or turn the shoulder back to the body?

Thanks.

First neck turning should be a combination that leaves close to .002" bullet tension between "your" chamber and "your" die.
With the expander ball doing little work if used.
Mine are. 012" when thick when finished.
And I machine into the shoulder with a 30° on the ground carbide tool, with a smaller than factory radius in the neck shoulder junction.
Pictured sharper than factory radius and fully machined shoulder..
This eliminates neck donuts.
Pictured, Before firing the FL die holds the bullet, after firing the bullet freely slides down the case neck, as pictured.

This is accomplished with a precision lathe and diamond tool grinder.
On thick brass like 30-06 I cut the whole shoulder as much . 008"

Finishing up a 510 Whisper today.

 

[SigSauerM7]

Holy crap.

At 65k PSI, you guys (45-70) are approaching 24 inch 8mm Mauser performance in 16 inch barrels potentially.

Good job!!

225gr at near 2500fps is impressive.

A slicked up Boat tail would be good to 1600yards+

Not bad. Bigger is better.

 

[wgranvilleb]

So I just visited the Maker bullet site for the 350 gr 338 expanding ....thinking of trying a few.
It now says KEEP UNDER 1000 FPS!..
Their ONE load data is 15.9 gr of 296/ H110.
Probably should be running these 900 to 950 fps Max to be safe with the 8.6 3 twist.

@45-90
As a bit of follow-up for this discussion . . .

I called Maker today and spoke with Paul, asking for clarification on the velocity max published on the website for the 350 gr projectiles (1050 fps on one page and 1000 fps on another). In short, Paul's rating is based on a concern for folks loading / testing in a colder climate and shooting in a hotter climate (pushing high-velocity range subsonics over to supersonic levels) and possibly becoming unsafe. However, he says he tests each batch before selling, and is using an 'opening' velocity of 1,130 - 1,150 fps range as 'safe' for general sale. So, loading and testing / shooting in warm weather should be safe at 1,050 fps.

 

[45-90]

@45-90
As a bit of follow-up for this discussion . . .

I called Maker today and spoke with Paul, asking for clarification on the velocity max published on the website for the 350 gr projectiles (1050 fps on one page and 1000 fps on another). In short, Paul's rating is based on a concern for folks loading / testing in a colder climate and shooting in a hotter climate (pushing high-velocity range subsonics over to supersonic levels) and possibly becoming unsafe. However, he says he tests each batch before selling, and is using an 'opening' velocity of 1,130 - 1,150 fps range as 'safe' for general sale. So, loading and testing / shooting in warm weather should be safe at 1,050 fps.

That's nice to know for all the 3 twist guys, and they should heed that advise...barrel length, and temperature change, will make a difference in velocities from these mostly temperature sensitive powders used.
I again, do not have to worry about it with the 6.5 twist, I ran them to almost 1700 fps, with excellent accuracy.
Finished loading for the 510 Whisper, I finally got around to building...tomorrow is .510 day.

 

[swandme]

No, if kept subsonic, the 300 gr Berger and 300 SMK were the most accurate in my 16" barrel...keep 285 ELDM below 1400 fps ...at 1400fps they did not make it to the 50 yd target.
Shoot without a muzzle device as they blow up as soon as they leave the confines of the barrel and destroy the muzzle device and the magneto speed bayonet.
My two best loads are 300 gr Berger 15.8 gr imr 4189 very consistent, and 300 gr SMK 15.8 gr Accurate 1680 are both accurate. And just about the only ones worth considering as this is a subsonic caliber, with too much capacity for subs and too little for high velocity. Plus lighter lead bullets blow up and copper too slow be of any use and inaccurate in the 3 twist. IMO...the 8 6 Blackout is a fun expensive 300 gr 338 Sub plinker.

Just checking if I read this wrong

Is it 4189 or 4198

Thanks for sharing the info

 

[swandme]

That's nice to know for all the 3 twist guys, and they should heed that advise...barrel length, and temperature change, will make a difference in velocities from these mostly temperature sensitive powders used.
I again, do not have to worry about it with the 6.5 twist, I ran them to almost 1700 fps, with excellent accuracy.
Finished loading for the 510 Whisper, I finally got around to building...tomorrow is .510 day.

We call our 511 short

690 ball sub or up 1620

It’s a hoot

 

[45-90]

Just checking if I read this wrong

Is it 4189 or 4198

Thanks for sharing the info

Nope, I typed it wrong...imr 4198 is correct. Thanks.

 

[DRWilson]

Because hybrid brass is hard to source, it will be about modifying @45-90 data for his 6.5 twist loads on regular brass. I’ll begin mine in early fall on regular brass. Has anyone started adjusting his loads development to support lower pressure cases? Thx!!

 

[45-90]

Because hybrid brass is hard to source, it will be about modifying @45-90 data for his 6.5 twist loads on regular brass. I’ll begin mine in early fall on regular brass. Has anyone started adjusting his loads development to support lower pressure cases? Thx!!

I would suggest getting Alpha Munitions 8.6 blackout brass, if one can not find hybrid brass cases.
It handles high pressures better than "regular" factory brass.
I've seen it $118 per hundred free shipping, but it's usually around $125 per hundred.
Plus no neck turning, or case forming.
I was going to order some, and try it, but am into the 510 Whisper loading at this time...it brings a crazy variety of loads with lots of power.
Example is the 1002 gr 1.175 BC bullet that starts out at 1100 fps sub load with a muzzle energu of 2700 ft/lbs and gets to 1000yds with 2000 ft/ lbs of energy!

Remember I did the test on the 3 twist vs the 6.5 twist and pressure signs show up heavy on the brass cases like 3 grains sooner with the 3 twist barrels on supers...in my rifles, ..note the Faxon 3 twist has very poor rifling, when new, it was torn, pitted, and galled...for that reason alone printing 6.5 twist data isn't all that helpful for horribly rifled 3 twist...unless one works up slowly...depending on how their rifling turned out, especially in early barrels.
Plus the 350 Maker can be ran as fast as one can shoot it in the 6.5 twist without fear of damaging the muzzle devices.
Always remove muzzle devices when testing new bullets and all high velocity loads.
Pushing the 350 Maker close to 1700 fps in this ladder test in the 6.5 twist with good accuracy, no bullet failures. This could be done in any 6.5 twist and Alpha Munitions cases...as I can add another 10 to 15 thousand psi to this load with machined hybrid cases...but I do not find it necessary to do that at this time, for another 100 fps, or so.

 

[SigSauerM7]

Can the gas tube on an AR10 handle 80k psi? 70k psi?

63-65k seems okay.

Can a BEEFED up bolt face handle 70k PSI or 80k PSI? (Bigger then LMT and KAC by 50-80% in length and girth).?

Larger and deeper barrel extension welded to monolithic upper to match?

After analyzing the XM7...I think the HK417 or AR10s can be made to reliably handle more pressure safely and reliably.

Sub MOA 6 lb Magnum powered AR10s should be doable with Special casings.

The newest HK417 is really REALLY accurate.

 

[45-90]

Can the gas tube on an AR10 handle 80k psi? 70k psi?

63-65k seems okay.

Can a BEEFED up bolt face handle 70k PSI or 80k PSI? (Bigger then LMT and KAC by 50-80% in length and girth).?

Larger and deeper barrel extension welded to monolithic upper to match?

After analyzing the XM7...I think the HK417 or AR10s can be made to reliably handle more pressure safely and reliably.

Sub MOA 6 lb Magnum powered AR10s should be doable with Special casings.

The newest HK417 is really REALLY accurate.

I'd say absolutely... Not.
On the AR 10.
I run 62,000 psi magnum loads in mine and a definite 65,000 psi self imposed limit, I don't go to on a daily basis.
Those higher pressures have not been tested on a regular basis to insure you will not blow up your firearm and your face.
I use KAK industries boltcarrier group and upper reciever for the short mags, as they are designed for short mags but still limit the pressure to 62,000 to max of 65,000 psi.
The only weapon designed to for that is the military weapon from Sig for around $10,000, that one can purchase, when available.

 

[SigSauerM7]

I'd say absolutely... Not.
On the AR 10.
I run 62,000 psi magnum loads in mine and a definite 65,000 psi self imposed limit, I don't go to on a daily basis.
Those higher pressures have not been tested on a regular basis to insure you will not blow up your firearm and your face.
I use KAK industries boltcarrier group and upper reciever for the short mags, as they are designed for short mags but still limit the pressure to 62,000 to max of 65,000 psi.
The only weapon designed to for that is the military weapon from Sig for around $10,000, that one can purchase, when available.

Looking at the KAK bolt now online.

What if you made the lugs 20mms long and 8mm's wide. And the sides of the Cam pin hole double thick where they like to give out.

Double thick barrel extention to match obviously.

Would need a 50,000 round stress test.

$$$$$$$$$.

 

[SigSauerM7]

I mean a Magnesium XM7 is light enough but they recoil like a G3.

Out classed by quality DI guns in MANY regards.

Like a light 180gr .25 Creedmoor Hybrid at 64k PSI DI gun outclasses the XM7 pretty well in terms of recoil mitigation and drop.

 

[Vynz]

I don’t have the skill set to do what @45-90 does, but I enjoy reading these posts knowing that in 20years when factory ammo is all hybrid case and firearm manufacturing is making rifles that can handle these pressures - I’ll be able to play with the same things he’s playing with today.

 

[Chipster697]

I read through the starting pages of this thread before ordering a Fix rifle about a year ago. Thank goodness I only paid about 50% of retail for it. Since my can finally showed up, I read the last 5 pages here and confess it’s just depressing. For me, 8.6 Blackout only is interesting as a subsonic cartridge.

What I am reading here is (1) my Faxon barrel probably is garbage, (2) the case capacity is too great for subsonic loads with most powders, and (3) the 1:3 twist rate is a gimmick.

My accuracy with Gorilla 210 grain Barnes TSX bullets was just bad. I thought the ammo might be at fault because I built a couple AR-15s with Faxon barrels with reasonable acceptable accuracy.

The only powders I have on hand that might be good for subsonic 8.6 loads are AA 1680 and TrailBoss. I probably will get some H110 for other applications. Using one of those powders, what bullet would you recommend starting with?

Is getting Quickload an essential first step? I was considering that but then heard that SAAMI approval might happen in January. Hornady killed that because of twist rate AFAICT.

Candidly, what I’m reading here is so discouraging that I’m considering just not pursuing 8.6 Blackout at all. I could get a nice .308 barrel for the Fix and concentrate on susbsonic loads for my Marlin 45-70.

Please tell me that I’m being too pessimistic about 8.6 Blackout…

 

[Vynz]

Chipster,

I think you are pretty correct in your assessment of 8.6Blackout with current factory loads, current rifle offerings, and failing to get SAAMI support. But I don’t think it will always be this way. If you read 45-90’s later posts, using a 1:6.5 twist he has a fully functioning dual use rifle/cartridge with well performing supers and good subs. So I wouldn’t be permanently pessimistic but I’ve certainly put all 8.6Blk plans to rest labeling it as needs more time to develop. I think Q tacitly understands this as they have delayed their Boombox by over 4 months without a word since SHOT.

 

[wgranvilleb]

@Chipster697:

Yes, it has also been a learning curve for me as well, as the excitement from the market hype has given way to the reality of its capabilities. Expectations drive satisfaction or disappointment, which is likely a central issue with this.

I have posted a fair amount of load data, both super and subsonic data, from a 12" 1:3" twist barrel. Recently, I have loaded a final batch of rounds to supplement the earlier data, and I would like to wrap this phase up for now. I do have a 16" barrel that I will develop loads for and will publish when available.

In short, I agree with your assessment that this caliber, in the 1:3" twist configuration is mostly a subsonic round. The subsonic performance is interesting, and I have achieved ~ MOA performance at 100 and 300 yards. With the Porq Chop, the gun is impressively quiet. For load development, the 300 gr SMK, and Maker 300 gr and 350 gr projectiles work well.

For super-sonic applications, (again, with the 1:3" twist), the performance and the latitude of available projectiles is discouraging. Bearing in mind, that projectile selection is limited to solid copper or bonded. Barnes TSX/TTSX projectiles need ~1,800 fps to function, which is near the muzzle velocity for the heavier options (185 gr, 210 gr), and limits effective use to ~100 yards. The Barnes 160 gr muzzle velocity is a bit higher, probably reaching out to 150 yards or so. Another attractive option is the Maker 220 gr option which is likely the best all-around supersonic option, designed to function in the 1,500 - 1,900 fps envelope, extending the range a bit further. To directly address your question, I would start with the Barnes 160gr projectile for a velocity (only) best case design, and increase weight from that point.

Regarding barrels and twist rate . . . I personally only have experience with Q barrels, and have been satisfied. I have read too much about other brand barrels not performing satisfactorily and would not consider as a viable option. Another manufacturer, Mos-Tec (https://mos-tek.com/) is worth considering, as they offer additional twist rates of 1:5", and 1:6", which allows for wider projectile selection and much higher muzzle velocities.

Regarding powders . . . The data I have generated is with H110, CFEBLK, H4227, A1680, and H335 (too slow). Any of the first four powders are fine, with H110 being efficient (least powder weight for velocity), however, at this point, I favor H4227 (slightly). Overall, pressure limits will be reached with all of the four. A powder I haven't tested yet is H4198, which looks interesting.

Summary . . .
I have come to accept that with the 1:3" twist, subsonic performance out to 300 yards, and supersonic performance is reliable to 100 - 150 yards. Slowing the barrel twist to 1:5" - 1:6.5" will greatly increase the super-sonic performance and projectile latitude.

With The Fix, which is what I own, I plan to use the 6.5 CM barrel if I need to reach out beyond the capability of the 8.6 barrel, or alternatively, one could opt for the .308 to fill the gap between 8.6 and 6.5.

Best of luck with your efforts . . .

 

[Chipster697]

@Chipster697:

Yes, it has also been a learning curve for me as well, as the excitement from the market hype has given way to the reality of its capabilities. Expectations drive satisfaction or disappointment, which is likely a central issue with this.

I have posted a fair amount of load data, both super and subsonic data, from a 12" 1:3" twist barrel. Recently, I have loaded a final batch of rounds to supplement the earlier data, and I would like to wrap this phase up for now. I do have a 16" barrel that I will develop loads for and will publish when available.

In short, I agree with your assessment that this caliber, in the 1:3" twist configuration is mostly a subsonic round. The subsonic performance is interesting, and I have achieved ~ MOA performance at 100 and 300 yards. With the Porq Chop, the gun is impressively quiet. For load development, the 300 gr SMK, and Maker 300 gr and 350 gr projectiles work well.

For super-sonic applications, (again, with the 1:3" twist), the performance and the latitude of available projectiles is discouraging. Bearing in mind, that projectile selection is limited to solid copper or bonded. Barnes TSX/TTSX projectiles need ~1,800 fps to function, which is near the muzzle velocity for the heavier options (185 gr, 210 gr), and limits effective use to ~100 yards. The Barnes 160 gr muzzle velocity is a bit higher, probably reaching out to 150 yards or so. Another attractive option is the Maker 220 gr option which is likely the best all-around supersonic option, designed to function in the 1,500 - 1,900 fps envelope, extending the range a bit further. To directly address your question, I would start with the Barnes 160gr projectile for a velocity (only) best case design, and increase weight from that point.

Regarding barrels and twist rate . . . I personally only have experience with Q barrels, and have been satisfied. I have read too much about other brand barrels not performing satisfactorily and would not consider as a viable option. Another manufacturer, Mos-Tec (https://mos-tek.com/) is worth considering, as they offer additional twist rates of 1:5", and 1:6", which allows for wider projectile selection and much higher muzzle velocities.

Regarding powders . . . The data I have generated is with H110, CFEBLK, H4227, A1680, and H335 (too slow). Any of the first four powders are fine, with H110 being efficient (least powder weight for velocity), however, at this point, I favor H4227 (slightly). Overall, pressure limits will be reached with all of the four. A powder I haven't tested yet is H4198, which looks interesting.

Summary . . .
I have come to accept that with the 1:3" twist, subsonic performance out to 300 yards, and supersonic performance is reliable to 100 - 150 yards. Slowing the barrel twist to 1:5" - 1:6.5" will greatly increase the super-sonic performance and projectile latitude.

With The Fix, which is what I own, I plan to use the 6.5 CM barrel if I need to reach out beyond the capability of the 8.6 barrel, or alternatively, one could opt for the .308 to fill the gap between 8.6 and 6.5.

Best of luck with your efforts . . .

Thanks for your replies. I will get some H110 and SMK 300s, but will start with the 1680 since that is the only “published” load data. I have other uses for H110 so it won’t go to waste. We’ll have to see what my barrel does accuracy wise.

 

[wgranvilleb]

@Chipster697:

I suggest you refer to prior posts #850 and #837 for starting point data.

Remember: 12" Q barrel, 1:3" twist

 

[45-90]

Picture of a 6.5CM from American Rifleman 120 gr copper bullet twist 1-8, velocity 2777 fps.
Notice the close together swirls, the appearance of extra distruction from rotation, in clear gel. Yes it's all hype.

Yes I've spent a lot of time with the 8.6 Blk
And gave up on the 3 twist not long after I received mine.
I did not give up on the cartridge, figuring it was the rough rifled barrel and it's limiting twist range.
So I purchased a special McGowen 6.5 twist and chambered it myself.
The 6.5 twist will stablize any bullet available today in 338 cal even the 350 gr, plus no velocity limitations and great accuracy.

So it's barrel quality and twist rate that is the main problem. And close to the 338 Federal in super velocity where slower powders are utilized and 3000 ft/lbs of muzzle energy are available.
2800 fps with 160 gr Barnes, light recoil flat shooting, or go to 350 subs with accuracy, up to 1700 fps max velocity with powder selected. I have tons of load data...

But this it's mostly all no good for 3 twist barrels, which most have.

I have all the machine tools and knowledge to build an AR 10 barrel in 6.5 Twist from a quality barrel blank. Just have to machine a few extra features, gas port, gas journal, barrel extension.
I have done this before, but I build 16" or longer these days...not into SBRs, just my choice.
Since almost no one does this, someone who manufacturers "quality" AR 10 barrels,
should step up and offer a choice, in a 6.5 twist.
I usually don't chamber AR 15 and AR 10 from barrel blanks, except if I want something unusual like a 30 RAR in AR15, or 338 RCM in AR 10...the latest two obsolete cartridges, I thought had merit in sn AR platform.
I usual buy a ready chambered AR barrel for a build, like everyone else to assemble in my chosen build.
To bad quality 8.6 Blk barrels in slower twists are not readily available, from a variety of quality venders, like the 300 BO.

 

[Mike6158]

I think I found the candidate for my bolt gun build. Remington makes a model 783 rifle with a heavy threaded barrel in .308. My local gun store is going to call and order one for me. It comes with a butt ugly tan stock but I can fix that later. Remage makes a 8.6BLK replacement barrel for that rifle. I'm hoping .45-90 will chime in and give me some advice on barrel length. Twist rate available is 1:3, 1:6, 1:8, and 1:9. Unless advised otherwise I'll go with the 1:6 twist. It'll be heavy. I'm going with a straight bull barrel. Max length available is 27". Shortest is 8".

 

[45-90]

I think I found the candidate for my bolt gun build. Remington makes a model 783 rifle with a heavy threaded barrel in .308. My local gun store is going to call and order one for me. It comes with a butt ugly tan stock but I can fix that later. Remage makes a 8.6BLK replacement barrel for that rifle. I'm hoping .45-90 will chime in and give me some advice on barrel length. Twist rate available is 1:3, 1:6, 1:8, and 1:9. Unless advised otherwise I'll go with the 1:6 twist. It'll be heavy. I'm going with a straight bull barrel. Max length available is 27". Shortest is 8".

I tried the 3 twist, that was a disaster for me, very limiting in velocity, and damaged the muzzle brake and the magneto speed bayonet in one shot.
I went with the 6.5 twist...a 6 twist would be similar, and 24" Rem Varmit contour. For total satisfaction with the 8.6 Blackout.
Accuracy is great, and velocity is not limited with supers or subs.
350 Maker at 1700 fps or sub sonic no problem with bullet blow ups, or bullet stability, it's as versitle as the 300 Blackout with no down sides. Cheap lead bullets from Speer acurate at high super velocity or subs.
I use hybrid cases in mine, but the new 8.6 BO Alpha Munitions cases will do well, and handle pressure
I ordered two McGowen barrel blanks, one 6.5 twist .338 for 8.6 Blk, and a 10 twist .510 for the .510 Whisper, along with the 300 Blk. I've got subsonic covered.
I have load data for just about every .338 bullet weight, with the 6.5 Twist 160 Barnes to 350 Maker. One can add about 3 more grains of powder over my 3 twist before reaching the same pressure signs in the 6.5 twist...for much higher velocity.
Pics, the 338 and .510 barrel blanks
Testing the 350 Maker to 1700 fps, in the 6.5 twist without the muzzle device...to make sure. Maker limits them to 900 to 1000 fps for the 3 twist on their web page.
And the .510 Whisper 750 Amax next to the 350 gr 8.6 Maker.
Start to finish, on both 8.6 and 510 Whisper.
If you want versatility and better accuracy with no velocity limitations on any bullet, get the 6.5 twist.

 

[Tyranny Not Allowed]

I tried the 3 twist, that was a disaster for me, very limiting in velocity, and damaged the muzzle brake and the magneto speed bayonet in one shot.
I went with the 6.5 twist...a 6 twist would be similar, and 24" Rem Varmit contour. For total satisfaction with the 8.6 Blackout.
Accuracy is great, and velocity is not limited with supers or subs.
350 Maker at 1700 fps or sub sonic no problem with bullet blow ups, or bullet stability, it's as versitle as the 300 Blackout with no down sides. Cheap lead bullets from Speer acurate at high super velocity or subs.
I use hybrid cases in mine, but the new 8.6 BO Alpha Munitions cases will do well, and handle pressure
I ordered two McGowen barrel blanks, one 6.5 twist .338 for 8.6 Blk, and a 10 twist .510 for the .510 Whisper, along with the 300 Blk. I've got subsonic covered.
I have load data for just about every .338 bullet weight, with the 6.5 Twist 160 Barnes to 350 Maker. One can add about 3 more grains of powder over my 3 twist before reaching the same pressure signs in the 6.5 twist...for much higher velocity.
Pics, the 338 and .510 barrel blanks
Testing the 350 Maker to 1700 fps, in the 6.5 twist without the muzzle device...to make sure. Maker limits them to 900 to 1000 fps for the 3 twist on their web page.
And the .510 Whisper 750 Amax next to the 350 gr 8.6 Maker.
Start to finish, on both 8.6 and 510 Whisper.
If you want versatility and better accuracy with no velocity limitations on any bullet, get the 6.5 twist.

Do you have any data on the kinds of group sizes you are able to obtain with 300gr or 350gr Maker bullets, at subsonic velocities with that slower twist barrel?

 

[45-90]

Yes, H335 gives maximum velocities, with total case fill, 2800 fps for the 160 gr Barnes, and good accuracy....this is 65,000 psi area not 80,000 that the hybrid csses are capable of, according to QL.

 

[Tyranny Not Allowed]

Yes, H335 gives maximum velocities, with total case fill, 2800 fps for the 160 gr Barnes, and good accuracy....this is 65,000 psi area not 80,000 that the hybrid csses are capable of, according to QL.

Oh I was looking for subsonic. Please and thank you!

 

[45-90]

Oh I was looking for subsonic. Please and thank you!

Seems like there would be a bunch of subsonic data out there as that's what most are doing, it would appear...except me, I've been going full on supers from 160 gr 2800 fps to 350 maker at 1700 fps.
But I do shoot subs, the Maker recommended load for 3 twist was 1129 fps in my 6.5 twist, exceeding the 1050 max. But I haven't group shot it, but the supers in 350 Maker are very accurate.
I tend to shoot the 300 gr Berger 15.8 gr IMR4198 and the 300 SMK 15.8 gr of AA 1680 for subs. With accurate results.
They hit low on the target cause it was sighted for supers , but this is 300 SMK sub load with 1680 in the 6.5 twist.
And a Red Dot load, at close to max pressure, so 865 fps is about all there is, and it's so slow small velocity variatons, make a big difference vertically on the target. but it's quiet,

 

[Mike6158]

I went with the 6.5 twist...a 6 twist would be similar, and 24" Rem Varmit contour. For total satisfaction with the 8.6 Blackout.
Accuracy is great, and velocity is not limited with supers or subs.
350 Maker at 1700 fps or sub sonic no problem with bullet blow ups, or bullet stability, it's as versitle as the 300 Blackout with no down sides. Cheap lead bullets from Speer acurate at high super velocity or subs.
I use hybrid cases in mine, but the new 8.6 BO Alpha Munitions cases will do well, and handle pressure
I ordered two McGowen barrel blanks, one 6.5 twist .338 for 8.6 Blk, and a 10 twist .510 for the .510 Whisper, along with the 300 Blk. I've got subsonic covered.
I have load data for just about every .338 bullet weight, with the 6.5 Twist 160 Barnes to 350 Maker. One can add about 3 more grains of powder over my 3 twist before reaching the same pressure signs in the 6.5 twist...for much higher velocity.
Pics, the 338 and .510 barrel blanks
Testing the 350 Maker to 1700 fps, in the 6.5 twist without the muzzle device...to make sure. Maker limits them to 900 to 1000 fps for the 3 twist on their web page.
And the .510 Whisper 750 Amax next to the 350 gr 8.6 Maker.
Start to finish, on both 8.6 and 510 Whisper.
If you want versatility and better accuracy with no velocity limitations on any bullet, get the 6.5 twist.

I'm committed or maybe I should be committed. The rifle is ordered. The worst case is I end up with a threaded heavy barrel .308. I held off ordering the 8.6 barrel until I see the profile of the barrel that is installed. I was going to order a bull barrel but that might not fit the stock so I held back. The new barrel will be 6 twist because that's what they offer. I could go 3 twist but I have that coming for the AR and don't need two 8.6's with 3 twist.

I liked what I see from you concerning your 6.5 twist barrel performance. It seems like a good sub and super twist rate.

I still haven't received the 3 twist barrel for the AR. It'll be for subs only since it's 3 twist. I'll be honest, I don't like dicking around with gas systems. I've got a very good adjustable gas block on it and most of the time the rounds eject as desired... but every now and then it'll sling one back and dent the mouth of the case. Plus there's the need for a brass catcher. Losing a round of Alpha Munitions brass is painful so far my AR doesn't get to play with the Alpha brass. I hold it back for the bolt gun.

 

[45-90]

I'm committed or maybe I should be committed. The rifle is ordered. The worst case is I end up with a threaded heavy barrel .308. I held off ordering the 8.6 barrel until I see the profile of the barrel that is installed. I was going to order a bull barrel but that might not fit the stock so I held back. The new barrel will be 6 twist because that's what they offer. I could go 3 twist but I have that coming for the AR and don't need two 8.6's with 3 twist.

I liked what I see from you concerning your 6.5 twist barrel performance. It seems like a good sub and super twist rate.

I still haven't received the 3 twist barrel for the AR. It'll be for subs only since it's 3 twist. I'll be honest, I don't like dicking around with gas systems. I've got a very good adjustable gas block on it and most of the time the rounds eject as desired... but every now and then it'll sling one back and dent the mouth of the case. Plus there's the need for a brass catcher. Losing a round of Alpha Munitions brass is painful so far my AR doesn't get to play with the Alpha brass. I hold it back for the bolt gun.

I cut and glue a piece of felt type material to the shell deflector to totally eliminate case dents...
I'd save the alpha brass for the boltgun too.

 

[wgranvilleb]

Load data for 8.6 BO:

The latest iteration of the 8.6 BO load data, with 12" and 16" barrel lengths (Q barrels, 1:3" twist).
The same brass lot was used for all testing and annealed after each firing.
CCI large rifle primers. Headspace: - 0.002" ; trim length: 1.685"
Magazine OAL limit: 2.800"
Velocity data via LabRadar.
None of the loads have been tested for accuracy, only velocity at this stage.

The solid sloping line is the 12" barrel.
The dashed sloping line is the 16" barrel.
The vertical lines on the supersonic charts represent a suggested 'max' and should be approached carefully.

Subsonic:
300 gr SMK projectile tested, as it appears to be commonly used.
COAL 2.780" ; Jump .050"
Target velocity: 1050 fps
Observation: The additional barrel length induces additional friction (for supers the added barrel length increases velocity).
Note: there is a velocity loss of only ~100 fps at 300 yards.

Supersonic:
Projectiles tested:
- 160 gr Barnes TTSX, COAL: 2.675" ; Jump: .110"
- 185 gr Hornady Cx, COAL: 2.672" ; Jump: .050"
- 220 gr Maker, COAL: 2.665" ; Jump: .050"
Powders selected from a broader set previously tested which seemed best suited.
Note regarding 'functionality':
- the Barnes bullet has a velocity minimum of 1,800 fps (max range of ~175 yds)
- the Hornady bullet has a velocity minimum of 2,000 fps (not suitable)
- the Maker bullet operates in a range of 1,500 fps - 1,900 fps (max range of ~125 - 175 yds)

 

[wgranvilleb]

More complete data set, FWIW . . . The solid sloping line is the 12" barrel, dashed is 16". Not all were tested in the 16" barrel.

Powder densities on the top right corner. In short, three are similar and 4227 is a little less dense.

My observations, FWIW:

CFE BLK: of the four, tends to be a bit more forgiving with pressure signs.
H110: tends to build pressure before velocity max is reached.
4227: subsonic testing offered the lowest SD and smallest groups (.8 MOA) @100 yds; slightly lower density with slightly greater case fill.

160 gr Barnes: best velocity with IMR 4227
185 gr Hornady Cx: best velocity with CFE BLK (not well suited for 8.6 BO applications)
220 gr Maker: best velocity with CFE BLK

 

[45-90]

Yesterday was, subsonic day with the 8.6 Blk and the .510 Whisper...
Cinclusion...The 510 whisper has a lot more power, ...alot.
But it also has a lot more recoil.
Recovered some of the bullets in the gravel bank.
Surprised to find the 350 gr Makers were like fmj ....they did not mushroom up, no petals opened like flowers, like the ballistics gel in pics. Some hollow points don't when one just puts a few layers of denim over the gel block.
Interesting,...what about hide, bone, and fat, sometimes do not let hollow points open.
Some insert a polymer tip.
It would be nice to observe these Makers in a bunch of actual kills.

 

[45-90]

Here is loads tried for the 350 gr Maker in the 8.6 Blkout...this is 6.5 twist, with mixed HS brass cases.
All loads fired at the same target.
Had to shoot left handed, cause I'm going blind in the right eye, and can not see the bullseye when it's cloudy, or sun is in the wrong position.
But the 350 gr Maker is accurate, when velocities are somewhat close. As 2 different times bullets of similar velocities got through the same hole...it's only 51 yds as measured by the range finder, but I wanted all loads on paper.
And subsonic I consider these bullets short range hunting, or tree stand type bullets, 100 to 125 about the limit ...as to there velocity restrictions on opening up, on game, inside 80 yds would be best.
And none found, opened up in dirt and gravel, at about 60 yds from these subsonic muzzle speeds. But fmj was almost, or more effective in dirt and gravel as the 350 gr Maker.

 

[45-90]

Found an accurate cheap bullet 30 cents delivered, for the 8.6 Blk, a 272 gr fmj. Shot a bunch of them subsonic. In the 6.5 twist, 16 gr INR4198 and 15 gr IMR 4227 both accurate, with IMR 4227 having slight better consistency in velocity.
For those with 3 twist, my 3 twist could shoot fmj bullets several hundred FPS faster without blowing up, then conventional lead bullets. These are cheap plinking bullets, and fairly accurate. So I ordered another 500.
This is my first attempt at left handed shooting. But you get the idea.

 

[wgranvilleb]

@45-90: thanks for the very informative follow-up, and your three part series.

Your experience with the 350 gr Makers projectiles is very interesting shooting 8.6 BO subsonic with 1:6.5" twist, and experiencing the lack of opening. I have attached a picture of recovered projectiles of the same round from earlier this year shooting subsonic at 300 yards with a Q Fix 1:3" barrel. The projectile on the left hit a steel gong (note the steep angle of impact) and the second is recovered from the dirt birm at 300 yards.

It is interesting the subsonic projectiles open with 1:3" twist, yet failed to open with 1:6.5" twist.

Regarding the supersonics, totally agree that the aggressive 1:3" twist rate limits velocity. Mos-tek is now offering 8.6 barrels with twist rates of 1:3", 1:5", and 1:6.5". Their initial impression is the 1:5" may represent a sweet spot to maintain energy and accuracy with subs, yet raise the supersonic velocity ceiling imposed by the 1:3". Another rabbit hole. . .

Regarding the inexpensive plinking ammo you found, do you think it will stand up to the 1:3" twist rate? Where are you sourcing it at that price?

Thanks for all of the follow-up, all greatly appreciated.

 

[45-90]

@45-90: thanks for the very informative follow-up, and your three part series.

Your experience with the 350 gr Makers projectiles is very interesting shooting 8.6 BO subsonic with 1:6.5" twist, and experiencing the lack of opening. I have attached a picture of recovered projectiles of the same round from earlier this year shooting subsonic at 300 yards with a Q Fix 1:3" barrel. The projectile on the left hit a steel gong (note the steep angle of impact) and the second is recovered from the dirt birm at 300 yards.

It is interesting the subsonic projectiles open with 1:3" twist, yet failed to open with 1:6.5" twist.

Regarding the supersonics, totally agree that the aggressive 1:3" twist rate limits velocity. Mos-tek is now offering 8.6 barrels with twist rates of 1:3", 1:5", and 1:6.5". Their initial impression is the 1:5" may represent a sweet spot to maintain energy and accuracy with subs, yet raise the supersonic velocity ceiling imposed by the 1:3". Another rabbit hole. . .

Regarding the inexpensive plinking ammo you found, do you think it will stand up to the 1:3" twist rate? Where are you sourcing it at that price?

Thanks for all of the follow-up, all greatly appreciated.

I don't think it's the twist rate, as I also have a 3 twist to try them in.
I think it's the medium, mostly gravel.
If I shot them in mud or ballistics gel they would open the same, regardless of twist.
I was concerned about how they perform on animals, not gravel, and was concerned about hide and heavy bone, bending them first, causing them not to open up.

Since I have both twist rates, I should be able to perform tests on that very subject.
Both subsonic, fired into the same soft medium, just the 3 twist vs the 6.5 twist.
I expect no difference...but we'll see.
Been wrong before...
So far the 6.5 twist has all the advantages, subs, or supers, with any bullet, better accuracy, can't blow up bullets inside the muzzle device, and more speed, totally versatile with any bullet.

I have ran fmj 250 gr in my 3 twist, if I remember correctly to 1600 fps and still stayed together.
I have not tried this 272 gr bullet in the 3 twist...as I gave up on it for my purposes, but others who only run subs, like the 3 twist. But I felt the 8.6 was a good cartridge if given a slower twist barrel.
That's what's been working for me...so I just report on what I observe...you decide if it's right for you.

I purchased the 272 gr 338 fmj from American Reloading $30 per hundred delivered on sale just yesterday, cause I liked the accuracy I got for cheap plinking loads on a prior purchase.
Here is a pic of the bullets.
And a Barnes super opened up nicely in soft medium.
I don't check mushroom performance much, as I use the 8.6 for target and plinking, not hunting.
So 8.6 Blk with 300 gr match bullets at almost 2000 fps will actually be a LR plinker capable of 1000 yd hits.
Different strokes for different folks.

 

[45-90]

I don't think it's the twist rate. I think it's the medium the bullet is fired in.
I believe the expansion will be close to the same.
I have a 3 twist and a 6.5 twist to check that theory in when shot it soft medium or ballistics gel.
We'll see.
I've been wrong before.
The reasoning is because I shot them in gravel, which tears up everything.
I used a grave pit as I was shooting a few Armor piercing in the 510 whisper, these in the 50BMG are capable of penetrating 3/4" steel at 100 yds.
Look at how messed up the soft steel jacketed FMJs are, then look at the 3 recovered armor piercing, even broke one on half ...that's gravel.
Put them in soft medium like ballistics gel and none would be deformed at all...
Reason why I don't believe it's twist rate but impact with gravel.
I was concerned about those who hunt with the 8.6 as to whether or not these would open if point was plugged with hide, fat, deform on bone, etc so as not to open up, as pictured in the ballistics gel experiments.
Cleaning the bolt guns in 8.6 and 510 whisper, and tumbling a bunch of 8.6 cases. So in a few days I'll see if I can catch a few in soft medium and compare 3 twist to 6.5 twist both subs. Maybe even shoot the 3 twist in the gravel.

 

[SigSauerM7]

Nice. Looks good. Lots of good data .