8.6 Blackout accuracy and barrel twist

blhar15

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Apr 27, 2004
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I have been searching the threads on the 8.6 Blackout, and saw some issues with the 1:3 twist over spinning and causing damage to suppressors, etc. I probably should have researched more before I put my rifle together, but I used the Faxon 16" barrel on my Aero AR-10 build. I was zeroing it in yesterday and had no consistency in my groups.

I have a Trijicon Credo 1-8x scope using a Griffin Bushwacker suppressor and Gorilla 285gr. fracturing ammo, the stuff for the 16" barrels. Confirming everything was tight, still had issues. I did inspect my suppressor for any baffle strikes, but everything looks good there.

So wondering if anyone has some thoughts on this? Would I be better off going to the Mos-Tek 1:6.5 twist barrel? Different ammo? What twist is best for that 285gr?

Thank you
 
I have an ar10 11.5” Mos-Tex barrel 1:3 twist. Zeroed to 100yds. Gorilla 285gr expanding ammo. It doesn’t stack rounds. Probably 2moa rifle. But I am happy with that as it’s not meant for that level of accuracy. I also run a Hux-Wrx Magnum Ti suppressor with no issues on the system. But it only likes the gorrila ammo and has issues with other subs.
 
Yes the 8.6 Blackout has a lot of issues...and they are all true! So another suckered into this 3 twist propaganda ..at least I was skeptical...but I had to try it..."curiosity killed the cat" first the Faxon 3 twist barrel I got... ya could not see through it!..what the hell! Put a patch through it pieces of metal, small and long slivers came out ...borescope it was the worst barrel ever observed...torn, galled, pitted rifling ...really bad at the beginning as it not enough lube or not enough clearance ground on the button to make the 3 twist. So I lapped it with silicon carbide lapping compound and polished it...the beginning still some galling and torn areas, but the muzzle area was pretty fair. Problem is cartridge design too much capacity for subsonic too little capacity for supersonic.
Tried quite a few bullets did a fair amount of damage to muzzle devices and magneto speed bayonet destroyed.
What works, opened up the gas port to get bolt carrier lock back. 300 gr Berger bullets 15.8 gr imr4198, accurate low S/D capable. 300 gr SMK 15.8 gr AA 1680 accurate but higher S/D.
No other combinations were acceptable accuracy, except for close range hunting.
200 gr Speer will take 1600 fps
250 Sierra bt hunting fair keep velocity 1200 fps
285 gr eldm at 1400 fps will blow up before 50 yds.
So 1100 fps max for muzzle devices with these lead match bullets to be safe, all subsonic.
Copper bullets have not had acceptable accuracy so far...moved on to other projects.
But find the 300 match bullets from Berger and Sierra the only acceptable loads.
Here is my best acceptable load for the 8.6 blackout Faxon barrel after lapping& polishing...10 shots 9.4 S/D subsonic.
 

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Yes the 8.6 Blackout has a lot of issues...and they are all true! So another suckered into this 3 twist propaganda ..at least I was skeptical...but I had to try it..."curiosity killed the cat" first the Faxon 3 twist barrel I got... ya could not see through it!..what the hell! Put a patch through it pieces of metal, small and long slivers came out ...borescope it was the worst barrel ever observed...torn, galled, pitted rifling ...really bad at the beginning as it not enough lube or not enough clearance ground on the button to make the 3 twist. So I lapped it with silicon carbide lapping compound and polished it...the beginning still some galling and torn areas, but the muzzle area was pretty fair. Problem is cartridge design too much capacity for subsonic too little capacity for supersonic.
Tried quite a few bullets did a fair amount of damage to muzzle devices and magneto speed bayonet destroyed.
What works, opened up the gas port to get bolt carrier lock back. 300 gr Berger bullets 15.8 gr imr4198, accurate low S/D capable. 300 gr SMK 15.8 gr AA 1680 accurate but higher S/D.
No other combinations were acceptable accuracy, except for close range hunting.
200 gr Speer will take 1600 fps
250 Sierra bt hunting fair keep velocity 1200 fps
285 gr eldm at 1400 fps will blow up before 50 yds.
So 1100 fps max for muzzle devices with these lead match bullets to be safe, all subsonic.
Copper bullets have not had acceptable accuracy so far...moved on to other projects.
But find the 300 match bullets from Berger and Sierra the only acceptable loads.
Here is my best acceptable load for the 8.6 blackout Faxon barrel after lapping& polishing...10 shots 9.4 S/D subsonic.
Why would you go through all that when you could’ve just sent the barrel back?
 
Yes the 8.6 Blackout has a lot of issues...and they are all true! So another suckered into this 3 twist propaganda ..at least I was skeptical...but I had to try it..."curiosity killed the cat" first the Faxon 3 twist barrel I got... ya could not see through it!..what the hell! Put a patch through it pieces of metal, small and long slivers came out ...borescope it was the worst barrel ever observed...torn, galled, pitted rifling ...really bad at the beginning as it not enough lube or not enough clearance ground on the button to make the 3 twist. So I lapped it with silicon carbide lapping compound and polished it...the beginning still some galling and torn areas, but the muzzle area was pretty fair. Problem is cartridge design too much capacity for subsonic too little capacity for supersonic.
Tried quite a few bullets did a fair amount of damage to muzzle devices and magneto speed bayonet destroyed.
What works, opened up the gas port to get bolt carrier lock back. 300 gr Berger bullets 15.8 gr imr4198, accurate low S/D capable. 300 gr SMK 15.8 gr AA 1680 accurate but higher S/D.
No other combinations were acceptable accuracy, except for close range hunting.
200 gr Speer will take 1600 fps
250 Sierra bt hunting fair keep velocity 1200 fps
285 gr eldm at 1400 fps will blow up before 50 yds.
So 1100 fps max for muzzle devices with these lead match bullets to be safe, all subsonic.
Copper bullets have not had acceptable accuracy so far...moved on to other projects.
But find the 300 match bullets from Berger and Sierra the only acceptable loads.
Here is my best acceptable load for the 8.6 blackout Faxon barrel after lapping& polishing...10 shots 9.4 S/D subsonic.
Didn’t they say from the get go that supersonic loads with 1/3 twist had to use monolithic or bonded bullets? Using anything else is asking for trouble.
 
Didn’t they say from the get go that supersonic loads with 1/3 twist had to use monolithic or bonded bullets? Using anything else is asking for trouble.
That is correct and it sounds like 45-90 was using some bonded non solid copper rounds. That sucks that his gear got wrecked. I have not had any of those issues. The only “issues”I had was dialing in the gas block and getting the gun to run. I don’t run any supers out of my gas gun… only subs and the gun likes the gorilla 285gr. I have tested it (though expensive) with mag dumps etc and no feeding issues or ejection issues. It ran fine. I did have trouble with some hot loads from another manufacturer but got those sorted out.
 
The whole "spin energy" thing is a little bit off the deep end. You're talking about gaining 5-10% more kinetic energy at the expense of making most .338 bullets on the market non-viable and cornering yourself into a market of expensive monolithic bullets just to get away from complete failure.

Nevermind the fact that even if the bullet has that bonus kinetic energy, it has to have a method of delivery to a target... everything I've personally tested has over penetrated gloriously. AKA kinetic energy not delivered to the target...
 
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Didn’t they say from the get go that supersonic loads with 1/3 twist had to use monolithic or bonded bullets? Using anything else is asking for trouble.
Faxon changed the data.... early on their data included a lead 225 gr Hornaday bullet, that not only blew up as soon as it left the confines of the barrel, but blew primers ...as a bunch of use reported back to Faxon and they dropped that bullet and the load data... just go to Midway USA and look at the reviews under Faxon 3 twist 8.6 Blackout barrels ...You'll find it was us early customers who condemned the lead bullet load with its excessive pressure, & blow ups, and urged Faxon to drop it from their load data.
Which they did...
 
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That is correct and it sounds like 45-90 was using some bonded non solid copper rounds. That sucks that his gear got wrecked. I have not had any of those issues. The only “issues”I had was dialing in the gas block and getting the gun to run. I don’t run any supers out of my gas gun… only subs and the gun likes the gorilla 285gr. I have tested it (though expensive) with mag dumps etc and no feeding issues or ejection issues. It ran fine. I did have trouble with some hot loads from another manufacturer but got those sorted out.
We were following Faxon recommended load data, which has changed thanks to efforts of early customers they dropped the bullet off the load data that destroyed our equipment and blew primers...it was very dangerous. But it took months, maybe a year, to get it removed.
I asked if they would make me an 8 twist and I would just discard the 3 twist and take the loss and pay them for the 8 twist. It took 2.5 months to get a response, but they said they are under licensing agreement to make 8.6 Blackout 3 twist only...and gave me a coupon for 20% off anything in the store...I took the 450 Bushmaster...turned out to be a better rd for short range work. Their 16 twist will stablize resized 502 gr 458 bullets. And it delivers over 3000 ft/lbs of muzzle energy from a a lighter AR 15. Cheap bulk 45 cal pistol bullets 185gr to 230 gr, 390 gr Hornaday subs, that can be run as supers to resized 458 502 gr...no issues with any bullet subs or supers mixed, cheap to shoot for reloaders, and brings more energy up close within a 100 yds where most game would be shot. If I was subsonic plinking at steel at 500 the 8.6 blackout with 300 gr Berger makes sense...but game around 150 yds or closer the 450 Bushmaster brings more energy, 502 gr subs or 250 gr supers. No special, expensive, not available, iffy, copper bullets, required...some of which state not for 3 twist... Put a limb saver recoil pad on your AR 15 the 502 gr will go super if ya want, you'll notice the recoil...its light, handy, fast, no issues. I own both.
 
We were following Faxon recommended load data, which has changed thanks to efforts of early customers they dropped the bullet off the load data that destroyed our equipment and blew primers...it was very dangerous. But it took months, maybe a year, to get it removed.
I asked if they would make me an 8 twist and I would just discard the 3 twist and take the loss and pay them for the 8 twist. It took 2.5 months to get a response, but they said they are under licensing agreement to make 8.6 Blackout 3 twist only...and gave me a coupon for 20% off anything in the store...I took the 450 Bushmaster...turned out to be a better rd for short range work. Their 16 twist will stablize resized 502 gr 458 bullets. And it delivers over 3000 ft/lbs of muzzle energy from a a lighter AR 15. Cheap bulk 45 cal pistol bullets 185gr to 230 gr, 390 gr Hornaday subs, that can be run as supers to resized 458 502 gr...no issues with any bullet subs or supers mixed, cheap to shoot for reloaders, and brings more energy up close within a 100 yds where most game would be shot. If I was subsonic plinking at steel at 500 the 8.6 blackout with 300 gr Berger makes sense...but game around 150 yds or closer the 450 Bushmaster brings more energy, 502 gr subs or 250 gr supers. No special, expensive, not available, iffy, copper bullets, required...some of which state not for 3 twist... Put a limb saver recoil pad on your AR 15 the 502 gr will go super if ya want, you'll notice the recoil...its light, handy, fast, no issues. I own both.
That’s crummy about the early adoption hassle. Crazy dangerous what you went through. Now that bushmaster sounds interesting…. Hmmmm.
 
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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.
 
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That’s crummy about the early adoption hassle. Crazy dangerous what you went through. Now that bushmaster sounds interesting…. Hmmmm.
Here it is 16" barrel, 450 Bushmaster Fast 1-16" twist, AR 15 resize 458 500 gr Hornady bullet along with others...no issues. Any .452 or .458 bullet resized in cheap Lee sizing die, you can use any 45 caliber bullet on the planet. You can drill em out, & slit em, make your own...anyway you like...I haven't tried anything above 502 gr...no need really unless your going for elephants, or for fun...but this little AR 15 gets over 3000 ft-lbs of energy with lighter supers.
It beats the 458 SOCOM, with the fast twist, supers and subs...and you are not limited to just the light bullets. Hornady's 395 gr Sub is readily available and I shoot it at high velocity also, it's accurate either way...could be interesting on hogs with an extra 500 to 600 fps, on a sub sonic designed bullet...
 

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Why would you go through all that when you could’ve just sent the barrel back?
All the early barrels had issues, Faxon states it's difficulty in making the 3 twist, they were down to 1 twist and decided on 3 twist...so if ya wanted to see what it's about, ya pretty much had to use a crummy barrel...check out the early reviews...where guys state I can't see through it, it looks fuzzy. It's not just one barrel it was all early barrels... and today's are probably not much better... I wasn't expecting much, and didn't get much, from previous reviews...so I didn't put much money into it, just time lapping it. It was absolutely the worst barrel I've ever looked at through the borescope...no one else was making a 3 twist at the time... after experiencing problems, I wasn't ready to give up just yet. So I asked Faxon to make me an 8 twist in 8.6 and I'd just eat the cost of the 3 twist, and buy an 8 twist. They would not do that, because they are under a licensing agreement to make it in only 3 twist, to go with the 3 twist hype.
If I was serious about the 8.6 blackout caliber today... I'd just start with a match 8 twist 338 barrel blank and turn, chamber, thread for muzzle brake and barrel extension and drill the gas port. Just like I did for the 30 RAR cartridge.
Then you'd have an accurate cartridge with subs and supers, lead bullets would stay together, more economical and versatile.
 
All the early barrels had issues, Faxon states it's difficulty in making the 3 twist, they were down to 1 twist and decided on 3 twist...so if ya wanted to see what it's about, ya pretty much had to use a crummy barrel...check out the early reviews...where guys state I can't see through it, it looks fuzzy. It's not just one barrel it was all early barrels... and today's are probably not much better... I wasn't expecting much, and didn't get much, from previous reviews...so I didn't put much money into it, just time lapping it. It was absolutely the worst barrel I've ever looked at through the borescope...no one else was making a 3 twist at the time... after experiencing problems, I wasn't ready to give up just yet. So I asked Faxon to make me an 8 twist in 8.6 and I'd just eat the cost of the 3 twist, and buy an 8 twist. They would not do that, because they are under a licensing agreement to make it in only 3 twist, to go with the 3 twist hype.
If I was serious about the 8.6 blackout caliber today... I'd just start with a match 8 twist 338 barrel blank and turn, chamber, thread for muzzle brake and barrel extension and drill the gas port. Just like I did for the 30 RAR cartridge.
Then you'd have an accurate cartridge with subs and supers, lead bullets would stay together, more economical and versatile.
Glutton for punishment!
 
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Glutton for punishment!
Retired machinist...gotta have something to do. So messing around with inferior products and bad ideas, helps me understand human nature,...such that it is...And also, see if I can improve on them or make them work..for me, while keeping the mind active.

Did I tell ya about the time I marched in protest with King? And was under sniper fire at the Airport in South Africa, and arrested along with Mandela, while driving an 18 wheeler, and riding a million miles on amtrac...
 
That is correct and it sounds like 45-90 was using some bonded non solid copper rounds. That sucks that his gear got wrecked. I have not had any of those issues. The only “issues”I had was dialing in the gas block and getting the gun to run. I don’t run any supers out of my gas gun… only subs and the gun likes the gorilla 285gr. I have tested it (though expensive) with mag dumps etc and no feeding issues or ejection issues. It ran fine. I did have trouble with some hot loads from another manufacturer but got those sorted out.

If you're only running subs, why not do a 338 Spectre in an AR15? Seems like it would be far cheaper and easier to mess with compared to the 1:3 twist nonsense which appears to be giving some folks grief and locking them into expensive monolithic projectiles.
 
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If you're only running subs, why not do a 338 Spectre in an AR15? Seems like it would be far cheaper and easier to mess with compared to the 1:3 twist nonsense which appears to be giving some folks grief and locking them into expensive monolithic projectiles.
I actually looked into it, but the 10mm mag brass needed, was never instock...,& discontinued, by Midway, plus in a lighter AR 15 seemed like a real plus, and it was pretty accurate on video...so brass availability pushed me toward the 8.6 and the ridiculous 3 twist, so I had to try it...it's the wrong twist, too much case capacity for subs and too little for supers. And dangerous with lead bullets past 1100 to 1200 fps, as the bullets reach 400,000 rpm and pushed into 500,000 rpm they come apart as soon as they leave the confines of the barrel and destroy my muzzle device and the magneto speed bayonet...all on the first shot with Faxon recommended load with the only lead bullet recommended in their load data ...which has been since taken down after early complaints, of blowing primers and destroyed muzzle devices. Its mostly an expensive plinker for me with only two loads accurate enough to consider, in subs ...the copper bullets were not accurate, but they handled rotational super sonic speeds, but velocity is under manufacture recommendations for expansion...and many fast expanding copper bullets are not recommended for the 3 twist ....so it's very limited, and I would not recommend it to a friend, especially in the 3 twist.
 
I just went 338 Spectre because everything you need for it is more available. Already made in two different primer sizes for your preference. No ridiculous neck trimming and excessive case prep.

View attachment 8236170
I picked up an R700 chambered in 338S a few years ago off the PX here and have been kicking around the idea of getting a 6-8" AR upper built for it as well. But then I remember that I have a 9" 300BO upper that takes cheap powder coated .30cal projectiles which will do the same job (shooting steel quietly) as a 338S and I move that fun money towards something else.

The R700 came with dies and 600+ rds of loaded 338S ammo, so I'm set for life for brass :)
 
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If you're only running subs, why not do a 338 Spectre in an AR15? Seems like it would be far cheaper and easier to mess with compared to the 1:3 twist nonsense which appears to be giving some folks grief and locking them into expensive monolithic projectiles.
I actually ordered the bolt gun version before the AR version but then my state banned AR platforms so it forced my hand to buy all that stuff before I could fully research. I prefer that round in a bolt gun with folding stock over the AR platform but it is what it is.
 
I bought 300pcs of large pistol primer brass. I figure that oughta be a lifetime supply for a niche bolt action SBR that hosts multiple barrels and will likely only ever see 300gr Maker Subsonics.
Link to anything you've posted about your 338S bolt gun (build details, load data, etc), please? I think we've cluttered up this thread enough, haha.
 
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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.

Also really fast twist barrels if your loaded ammo has excessive runout or your shooting poor quality bullets... the fast twist will amplify what I call the premature wobble of the bullet as it makes the jump into the rifling. Accuracy will suffer.

Barrels with poor bore finish and or damage to the rifling from when it was made along with the really fast twist will also be another recipe for bullet failure. The bullet will take more of a beating and the really fast twist isn't going to help anything. The bullet might not be the problem and other factors are making it a problem.

Way before the 8.6 Blackout we made barrels for testing for a gun manufacturer in 30cal. in 5 twist, 3 twist, 2.5 twist, 2 twist, 1.5 twist and even tried 1-1 twist. The 1-1 twist we couldn't put enough clearance on the fast side of the tool so we where wiping out half of the land width so the lands where really narrow but finish wise the barrel was beautiful. I didn't charge them for the 1-1 twist barrel as it wasn't to spec. but I gave it to them anyways.

The Saami spec for twist for 8.6 BO is 1-5 twist.

Later, Frank
Bartlein Barrels
 
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.

Also really fast twist barrels if your loaded ammo has excessive runout or your shooting poor quality bullets... the fast twist will amplify what I call the premature wobble of the bullet as it makes the jump into the rifling. Accuracy will suffer.

Barrels with poor bore finish and or damage to the rifling from when it was made along with the really fast twist will also be another recipe for bullet failure. The bullet will take more of a beating and the really fast twist isn't going to help anything. The bullet might not be the problem and other factors are making it a problem.

Way before the 8.6 Blackout we made barrels for testing for a gun manufacturer in 30cal. in 5 twist, 3 twist, 2.5 twist, 2 twist, 1.5 twist and even tried 1-1 twist. The 1-1 twist we couldn't put enough clearance on the fast side of the tool so we where wiping out half of the land width so the lands where really narrow but finish wise the barrel was beautiful. I didn't charge them for the 1-1 twist barrel as it wasn't to spec. but I gave it to them anyways.

The Saami spec for twist for 8.6 BO is 1-5 twist.

Later, Frank
Bartlein Barrels

Frank

Interesting that the SAAMI spec is 1:5, while all the hype since the release has been 1:3. Seems the hype has killed a few animals (though I question whether they'd have lived if hit with the same bullet rotating a few K RPMs slower), along with a few suppressors, brakes, and chronos.

What's your take on 8.6BO?

@Frank Green
 
According to Berger stability calculator a 1-8 twist is all ya need with a 1.819" long 300 gr 338 bullet at 800 fps, 0 degrees, and 0 altitude...
It would run everything lead and copper supersonic, as well as subs. And my choice of twist if I were to make a barrel from a blank...it would be accurate and versatile.
 
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According to Berger stability calculator a 1-8 twist is all ya need with a 1.819" long 300 gr 338 bullet at 800 fps, 0 degrees, and 0 altitude...
It would run everything lead and copper supersonic, as well as subs. And my choice of twist if I were to make a barrel from a blank...it would be accurate and versatile.
That's what we've been telling guys. Most bullets we look at....don't need to be thru anything faster than a 7 twist.
 
Frank

Interesting that the SAAMI spec is 1:5, while all the hype since the release has been 1:3. Seems the hype has killed a few animals (though I question whether they'd have lived if hit with the same bullet rotating a few K RPMs slower), along with a few suppressors, brakes, and chronos.

What's your take on 8.6BO?

@Frank Green

You want my honest answer? I don't see a need for it. I'll never build one. You might as well have a 12ga shotgun with a rifled barrel and shoot slugs thru it for deer hunting. I'd think you would be better off. LOL! Ok probably a bad comparison.

I've got enough time with a 300AAC.... that I'll say this in closing. What will the 8.6BO do that the 300AAC won't do on a deer? Box ammo with 190gr or 200+gr bullets out of the AAC and subsonic and shoot 1/2moa groups at a 100 yards. What more can a guy ask for? My sons first rifle when he was 12 or 13 for deer hunting he wanted a AR15 in 300AAC. So I built him one. I like it so much I'm going to build myself one. We put my suppressor on his gun and he uses 135gr Hornady ammo for deer hunting. Plenty accurate and plenty of power to smoke a deer at 200 yards. For a walk around woods gun for deer hunting or sitting in the blind and you will be lucky to get a 150 yard shot. It's awesome.

To each is his own.... I guess if you really need a 338cal gun then I guess 8.6BO is it. I just don't see a need for it personally.

Like you said.... is a 5 twist or a 7 twist barrel with the bullet coming out at a slower rpm going to make a big difference on impact performance on the target or the deer your shooting? I think shot placement is more critical. As long as the bullet is stable to achieve proper accuracy. What are you gaining?

Later, Frank
 
You want my honest answer? I don't see a need for it. I'll never build one. You might as well have a 12ga shotgun with a rifled barrel and shoot slugs thru it for deer hunting. I'd think you would be better off. LOL! Ok probably a bad comparison.

I've got enough time with a 300AAC.... that I'll say this in closing. What will the 8.6BO do that the 300AAC won't do on a deer? Box ammo with 190gr or 200+gr bullets out of the AAC and subsonic and shoot 1/2moa groups at a 100 yards. What more can a guy ask for? My sons first rifle when he was 12 or 13 for deer hunting he wanted a AR15 in 300AAC. So I built him one. I like it so much I'm going to build myself one. We put my suppressor on his gun and he uses 135gr Hornady ammo for deer hunting. Plenty accurate and plenty of power to smoke a deer at 200 yards. For a walk around woods gun for deer hunting or sitting in the blind and you will be lucky to get a 150 yard shot. It's awesome.

To each is his own.... I guess if you really need a 338cal gun then I guess 8.6BO is it. I just don't see a need for it personally.

Like you said.... is a 5 twist or a 7 twist barrel with the bullet coming out at a slower rpm going to make a big difference on impact performance on the target or the deer your shooting? I think shot placement is more critical. As long as the bullet is stable to achieve proper accuracy. What are you gaining?

Later, Frank

Frank

Thanks for your input. I find myself in the same boat. I bought my 338S bolt gun more for giggles than anything else and I probably should have just bought a 300BO bolt gun as I was already shooting that round in an AR and reloading for it. While 338S doesn't really provide an answer to a question anyone was asking, 8.6BO does it in an even bigger and heavier gun with less parts compatibility and (apparently) an initial twist rate that's as effective at killing metal things attached to the ends of barrels as it is at killing animals.
 
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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.

Also really fast twist barrels if your loaded ammo has excessive runout or your shooting poor quality bullets... the fast twist will amplify what I call the premature wobble of the bullet as it makes the jump into the rifling. Accuracy will suffer.

Barrels with poor bore finish and or damage to the rifling from when it was made along with the really fast twist will also be another recipe for bullet failure. The bullet will take more of a beating and the really fast twist isn't going to help anything. The bullet might not be the problem and other factors are making it a problem.

Way before the 8.6 Blackout we made barrels for testing for a gun manufacturer in 30cal. in 5 twist, 3 twist, 2.5 twist, 2 twist, 1.5 twist and even tried 1-1 twist. The 1-1 twist we couldn't put enough clearance on the fast side of the tool so we where wiping out half of the land width so the lands where really narrow but finish wise the barrel was beautiful. I didn't charge them for the 1-1 twist barrel as it wasn't to spec. but I gave it to them anyways.

The Saami spec for twist for 8.6 BO is 1-5 twist.

Later, Frank
Bartlein Barrels

I was under the impression that there is no SAAMI spec for 8.6 BO yet. Is that some sort of preliminary/draft spec that is not published yet?
 
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I was under the impression that there is no SAAMI spec for 8.6 BO yet. Is that some sort of preliminary/draft spec that is not published yet?
The SAAMI spec is written and set. It will be officially released at shot show coming up. I’ve been told that by people on the SAAMI board and like I’ve said we’ve been making test barrels to that spec already and have more orders in process.
 
>With a 3 twist barrel you will have to limit your velocities to 1200fps or less.

Isn't that the primary use case for 8.6 BO anyway, ie, heavier subsonics - a "more powerful 300" (as I've seen it marketed)? If, for the sake of argument, everyone agrees subsonic is the primary use case for 8.6, then is the faster 1:3 twist rate a reasonable design decision given the bullet weight?

>Barrels with poor bore finish and or damage to the rifling
>I’ve been told that by people on the SAAMI board

Are SAAMI specs weighted towards a lowest common denominator, to accommodates looser real world tolerances?
 
Hasn't a lot of the marketing behind the 1/3 twist 8.6 BO been with full and fragmenting solids? Wouldn't think bullet separation is a primary concern with solids, just accuracy and terminal ballistics.
 
>With a 3 twist barrel you will have to limit your velocities to 1200fps or less.

Isn't that the primary use case for 8.6 BO anyway, ie, heavier subsonics - a "more powerful 300" (as I've seen it marketed)? If, for the sake of argument, everyone agrees subsonic is the primary use case for 8.6, then is the faster 1:3 twist rate a reasonable design decision given the bullet weight?

>Barrels with poor bore finish and or damage to the rifling
>I’ve been told that by people on the SAAMI board

Are SAAMI specs weighted towards a lowest common denominator, to accommodates looser real world tolerances?
If I'm understanding your questions correctly.....

"Isn't that the primary use case for 8.6 BO anyway, ie, heavier subsonics - a "more powerful 300" (as I've seen it marketed)? If, for the sake of argument, everyone agrees subsonic is the primary use case for 8.6, then is the faster 1:3 twist rate a reasonable design decision given the bullet weight?" Lets just say for example the 8.6BO is planned to run heavier subsonic bullets etc.... I just don't see a need for a 3 twist. So far I don't see a need for a 3 twist barrel. 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.

Someone needs to show actual test data in ballistic gelatin etc.... or some similar test that shows how a 3 twist with a given 338cal bullet performs better due to spin rate. I have yet to see anything. So if there isn't an advantage to having a really super fast twist to help bullet impact performance.... why do you need it? It's just going to have a negative effect on accuracy/flight of the bullet in my opinion until I see proof otherwise.

"Are SAAMI specs weighted towards a lowest common denominator, to accommodates looser real world tolerances?" Not sure exactly what your asking/saying here but I will say no. Like a lot of other things in the world you need to have standards. With no standards things will only be worse. By having a set standard for bore and groove size and twist (which really doesn't effect pressure), and a standard chamber spec. that's how you come up with maximum operating pressures and velocity figures. This way again.... you have a standard. Also the designer of the cartridge is the sole maker of the reference ammo. So when other gun makers or other ammo makers decide to tool up to make guns and or ammo and they do testing you have a set standard. So if they make changes to ammo for bullets, powder i.e. loads they can take the reference ammo to check the ammunition test barrel is giving proper pressure numbers etc. and that it is referencing properly. That way when they make and test they're ammo they know what is going on. Gun makers also have a min spec for the barrels. As long as they don't go under that min spec. they should be fine for production barrels not causing issues. If they chose to make the bore and groove sizes bigger or loosen up the chamber spec's for whatever reason they at least have a min. standard spec to go off of.

The question back to you is what is the lowest common denominator are you referring to? You are dealing with a lot of variables.

That answer your questions?
 
>Someone needs to show actual test data in ballistic gelatin etc.... or some similar test that shows how a 3 twist with a given 338cal bullet performs better due to spin rate.

Have you seen this marketing video from Faxon?


>what is the lowest common denominator are you referring to?

I was asking that in the context of your statement: "Barrels with poor bore finish and or damage to the rifling from when it was made along with the really fast twist will also be another recipe for bullet failure."

ie, with all the hype being 1:3, and SAAMI apparently coming in at 1:5, would they be making a judgement call about twist rate based on the real world variances you noted with respect to overall barrel quality (finish/rifling etc)?
 
>Someone needs to show actual test data in ballistic gelatin etc.... or some similar test that shows how a 3 twist with a given 338cal bullet performs better due to spin rate.

Have you seen this marketing video from Faxon?


>what is the lowest common denominator are you referring to?

I was asking that in the context of your statement: "Barrels with poor bore finish and or damage to the rifling from when it was made along with the really fast twist will also be another recipe for bullet failure."

ie, with all the hype being 1:3, and SAAMI apparently coming in at 1:5, would they be making a judgement call about twist rate based on the real world variances you noted with respect to overall barrel quality (finish/rifling etc)?

No I haven't seen that video they put out. So I just watched it now. What 210gr bullet was used? Also what type of ballistic gelatin is that also? What velocity was the bullets fired at? Was one 50fps faster then the other?

The video says a 9 twist vs a 3 twist. So let's say it's all accurate and that portrays shows that the 3 twist is making a slightly bigger wound cavity. Now show a test on a 5 twist vs a 3 twist? Would there be a difference?

Also you have to show more than just two blocks tested. It would be nice to know the data or shown more then just two blocks. What was the average for each when you shot it into 10 blocks from each twist? That would give you a clearer picture.

When places are doing testing for the FBI for bullets and they have to shoot into ballistic gelatin.... guess what... you are doing a lot of testing.

The designer of the cartridge or should I say the ammo maker that set the standard picks sets the spec's for the test barrel data/info. So if the 3 twist is so much better.... why isn't the 3 twist picked for the standard? Why did they go with 5 twist?

I might know who set the spec for it. I'll reach out to them and ask and see what I come up with.

Quality of the barrels bore finish etc... and again with really fast twist rates.... can make accuracy issues worse as well as effect bullets coming a part/blowing up right when they are leaving the barrel besides the velocity playing a part as well.
 
I did a gyro calc the other day on some .338 bullets and the 1:3" twist stuff had SG's in the 25-30 range in polar conditions... SG of 1.2 usually guarantees accuracy from a stability standpoint. 1.5 usually gets you all the BC you're going to get out of it. Before this the highest stuff I'd seen was in the 7-10 range.
 
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The video with a slightly larger wound channel is un convincing as to the virtues of the 3 twist being better...what was the respective velocities of each as it was fired into the gelatin? The 8.6 can have wild velocity swings and this one video shows not much difference,..as an animal hit in the vital area would be dead either twist. So why insist on something that is as problematic the 3 twist. That is a mistake and brings nothing beneficial to the table, as this video shows...shot to shot variation in the bullets and gelatin makeup, would so up with the same twist being used.
I have a 3 twist 8.6 and its very limited on bullet choices, and accur a cy is wholly lacking. The worst barrel interior I've ever inspected. Before giving up on the 8.6 I ordered a 338 6.5 twist and a 8.6 reamer is in the mail.
As it is with the 3 twist, I would not recommend the cartridge to a friend.
 
No I haven't seen that video they put out. So I just watched it now. What 210gr bullet was used? Also what type of ballistic gelatin is that also? What velocity was the bullets fired at? Was one 50fps faster then the other?

The video says a 9 twist vs a 3 twist. So let's say it's all accurate and that portrays shows that the 3 twist is making a slightly bigger wound cavity. Now show a test on a 5 twist vs a 3 twist? Would there be a difference?

Also you have to show more than just two blocks tested. It would be nice to know the data or shown more then just two blocks. What was the average for each when you shot it into 10 blocks from each twist? That would give you a clearer picture.

When places are doing testing for the FBI for bullets and they have to shoot into ballistic gelatin.... guess what... you are doing a lot of testing.

The designer of the cartridge or should I say the ammo maker that set the standard picks sets the spec's for the test barrel data/info. So if the 3 twist is so much better.... why isn't the 3 twist picked for the standard? Why did they go with 5 twist?

I might know who set the spec for it. I'll reach out to them and ask and see what I come up with.

Quality of the barrels bore finish etc... and again with really fast twist rates.... can make accuracy issues worse as well as effect bullets coming a part/blowing up right when they are leaving the barrel besides the velocity playing a part as well.
I agree, of course, it's just a marketing video and nothing conclusive can be drawn (that's why I'm researching it and seeking objective opinions about it - all I've seen is the hype).

I believe - but don't know for a fact - that it was Gorilla ammo as that's what it seems like all the Faxon/Q marketing videos feature:

Q/Faxon+Gorilla seem to be the primary marketing machine behind 8.6

Here's another one:


So why insist on something that is as problematic the 3 twist. That is a mistake and brings nothing beneficial to the table, as this video shows...shot to shot variation in the bullets and gelatin makeup, would so up with the same twist being used.
I have a 3 twist 8.6 and its very limited on bullet choices, and accur a cy is wholly lacking. The worst barrel interior I've ever inspected. Before giving up on the 8.6 I ordered a 338 6.5 twist and a 8.6 reamer is in the mail.
As it is with the 3 twist, I would not recommend the cartridge to a friend.

If I'm reading you correctly, the Faxon stuff has not impressed you? 😂 After absorbing the marketing of the 8.6 hype machine over the last few months, I was thinking maybe I'd discovered my Unicorn caliber. Something with substantially more range & power than .300 when running subsonic, while also being extremely quiet suppressed.

What's primarily motivating me these days is the tinnitus in my right ear - it's quite bad at this point after 35 years of .308. I'm at the point where I can't enjoy the range anymore unless everyone there is shooting suppressed (my right ear rings for a few days after a range day, even with multiple layers of hearing protection), and most of the hunting I do is 300-500 yards, so I've just never been a big fan of .300 (not dissing it - just never loved it), so I was thinking 8.6 might be my ticket to a quiet round with enough energy for the range I like to work at. All I've ever hunted with my entire life is .308...I'm not much into diversity...also I scored 100K rounds of crated .308 back in the mid-90's, so that contributed to my lack of motivation to diversify... 😀

There's a company I was looking at, GQ Armory, that sells very nice but also very expensive turnkey 8.6 builds and manufactures their own match grade 8.6 barrels. I spoke to the owner, Quinn, about some of this stuff (prior to inquiring on this forum). He expressed some similar, though not as strong, opinions about Faxon barrels. He was probably being diplomatic. His builds are very nice, well reviewed, but not cheap...of course nothing is these days. He seemed like a good guy on the phone - even though he is spooling up manufacturing his own cans for 8.6, he recommended I go for another brand (Diligent Defense DTF-LTI) if I chose to dive in right away. I'll call him back and get his thoughts on the 1:5 SAAMI spec, which I wasn't aware of, and if he plans to go that route with future barrels.

Here's a cool suppressor comparison video with 8.6:
 
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Watch the other video you posted in your post #36. Slow the video down and watch it really close at about the 13 or 14 second mark. Here is a still picture I took of it. Everyone or most people think that when the bullet leaves the barrel it leaves perfectly straight etc... it doesn't it. You can see in that video the bullet tipping down at the base. Now the bullet has to recover while in flight. The worse the tipping is and this can be caused by very high pressures as well. The more the bullet has to try and to recover.... usually the accuracy suffers.
 

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Thanks. Lookin' forward to hearing more about it!
I know who set the spec and I'm not going to name them out of respect but I deal with them a lot. These guys deal in the real world when it comes to ballistics and ammo and bullets etc....

They made the same comment back. They don't know why anyone needs a twist faster than 5.
 
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"If I'm reading you correctly, the Faxon stuff has not impressed you? 😂 "

No I'm not poking at them directly or in a bad way but after reading some of the posts in this and other threads you have to question.... what are you getting for a complete barrel ready to go for as low as a $155? I'll take a good guess that they are button rifled barrels and at that price point how consistent are the bore and groove sizes for dimensions and uniformity, bore finish, twist uniformity and chamber finish etc...?

The barrel in the rifle is the single most important part of the puzzle from an accuracy standpoint and barrel life etc...You can have the best action and stock in the world and glass sitting on top of it but put a mediocre barrel on the gun and most of the time you end up with a mediocre rifle. Take a decent quality action, bed it in a good stock do good gunsmithing work and put a very good barrel on the gun and most of the time you end up with a excellent shooting rifle.

I remember several years ago (probably 10-15 years) watching a documentary of a tour at a gun manufacturer that made AR/M16/M4 type rifles and they showed the manufacturing process to build the guns. I cringed when they showed the barrel finished with the front sight/gas block on it and then they took an arbor press with a dial indicator on and was straightening the barrels. If I would've had food in my mouth I probably would've choked on it. Then they said the price of the finished barrel back then to the US Gov't was $7 and that included the cost of the steel!

Does everyone need a high end barrel / built rifle? No they don't but keep in mind you get what you pay for.
 
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>Someone needs to show actual test data in ballistic gelatin etc.... or some similar test that shows how a 3 twist with a given 338cal bullet performs better due to spin rate.

Have you seen this marketing video from Faxon?


>what is the lowest common denominator are you referring to?

I was asking that in the context of your statement: "Barrels with poor bore finish and or damage to the rifling from when it was made along with the really fast twist will also be another recipe for bullet failure."

ie, with all the hype being 1:3, and SAAMI apparently coming in at 1:5, would they be making a judgement call about twist rate based on the real world variances you noted with respect to overall barrel quality (finish/rifling etc)?


So in that video we're looking at a Barnes 210 TTSX. You can see on the 1:3" twist gel impact, the bullet fragments (shears petals) and creates secondary smaller wound channels. Schools of thought on that differ depending on who you're talking to and what the application is, but one thing I will tell you from experience is that when you shed petals, especially on bullets that aren't designed to uniformly shear/shed petals, you cause asymmetry that makes the bullets go unpredictable directions in gel/tissue. You can see that in the wound track on the video vs. the top block, which is straight as an arrow. Typically straighter is better for hunting application especially situations like quartering shots etc.

IMO, you're taking excellent performing bullets-- some of the toughest most reliable bullets on the market-- and taking them to the brink of failure.
 
"If I'm reading you correctly, the Faxon stuff has not impressed you? 😂 "

No I'm not poking at them directly or in a bad way but after reading some of the posts in this and other threads you have to question.... what are you getting for a complete barrel ready to go for as low as a $155? I'll take a good guess that they are button rifled barrels and at that price point how consistent are the bore and groove sizes for dimensions and uniformity, bore finish, twist uniformity and chamber finish etc...?

The barrel in the rifle is the single most important part of the puzzle from an accuracy standpoint and barrel life etc...You can have the best action and stock in the world and glass sitting on top of it but put a mediocre barrel on the gun and most of the time you end up with a mediocre rifle. Take a decent quality action, bed it in a good stock do good gunsmithing work and put a very good barrel on the gun and most of the time you end up with a excellent shooting rifle.

I remember several years ago (probably 10-15 years) watching a documentary of a tour at a gun manufacturer that made AR/M16/M4 type rifles and they showed the manufacturing process to build the guns. I cringed when they showed the barrel finished with the front sight/gas block on it and then they took an arbor press with a dial indicator on and was straightening the barrels. If I would've had food in my mouth I probably would've choked on it. Then they said the price of the finished barrel back then to the US Gov't was $7 and that included the cost of the steel!

Does everyone need a high end barrel / built rifle? No they don't but keep in mind you get what you pay for.

Faxon is perfectly capable of making a barrel worth $150. It is exactly what you'd expect for the price. There's no shame in that and, FWIW, they stand behind their products. As much as I like Bartlein, I don't need a $400 blank to shoot CQB distance targets.

I've been pretty over rifle subs since the mid 2000s, can't say 8.6 changes that opinion. 1:3 sounded like a joke from the start.
 
Am, admittedly, new to the 8.6 parade, but really like it thus far. My application is target and hunting, and quieter is much much better. I've throw lots of 300BO rounds, sub and super; and the 8.6 is exclusively a sub gun. My setup is R700, Faxon 16" barrel, thunderbeast can, throwing 285 gorillas.
The first several were evaluated for whether they were hitting the target as intact projectiles vs petaling/expanding; I should think - with the press that is available - everyone would start in similar fashion. Being satisfied that rounds were not expanding at or near the muzzle, I went to suppressed fire - and it is very quiet. Not hollywood quiet, but close...

I whole-heartedly agree that the caliber is very application-specific, probably even platform-specific. I built it in 700 so if the whole thing goes tits up, I can use the action and chassis for something else.

I have not yet shot significant groups for accuracy, but was stacking holes at 50 yards, which is where it will see its primary usage.

I don't think anyone is buying an 8.6 and expecting a 308 experience - or no one should be. It is more along the lines of buying a kit car and figuring out if you can make it run well.

I like the round as a special-purpose thing, and like the gun I built. That said, I would have a hard time recommending it to anyone not doing with it exactly what I am doing with it.
 
Watch the other video you posted in your post #36. Slow the video down and watch it really close at about the 13 or 14 second mark. Here is a still picture I took of it. Everyone or most people think that when the bullet leaves the barrel it leaves perfectly straight etc... it doesn't it. You can see in that video the bullet tipping down at the base. Now the bullet has to recover while in flight. The worse the tipping is and this can be caused by very high pressures as well. The more the bullet has to try and to recover.... usually the accuracy suffers.
Yeah, I noticed that too when I first saw that video...however...it's really hard to tell from video if that is not an artifact of lens distortion or sensor distortion as a consequence of "rolling shutter" (the readout time from the camera sensor top to bottom is linear, so over a period of microseconds it results in angular distortion of moving objects in the direction of their motion). Point being...I'm not sure...it does seem odd that a bullet spinning that fast would start to nose up (or ass down) just a few inches out of the barrel...so...inconclusive in my view...

The thing I care about most at this point is suppressability...if that's a word...I want a powerful subsonic round that is as quiet as possible. What else besides 8.6 achieves that? .458 socom is pretty impressive...but the ballistics are more challenging than 8.6...

 
Yeah, I noticed that too when I first saw that video...however...it's really hard to tell from video if that is not an artifact of lens distortion or sensor distortion as a consequence of "rolling shutter" (the readout time from the camera sensor top to bottom is linear, so over a period of microseconds it results in angular distortion of moving objects in the direction of their motion). Point being...I'm not sure...it does seem odd that a bullet spinning that fast would start to nose up (or ass down) just a few inches out of the barrel...so...inconclusive in my view...

The thing I care about most at this point is suppressability...if that's a word...I want a powerful subsonic round that is as quiet as possible. What else besides 8.6 achieves that? .458 socom is pretty impressive...but the ballistics are more challenging than 8.6...



As others have noted, if you're only looking to shoot .338 subs, just go with a 338 Spectre or Razorback in an AR15 sized package and avoid the weight penalty from the AR10 as well as the (apparent) downsides of the 3 twist barrels shops appear hellbent on producing.
 
All the early barrels had issues, Faxon states it's difficulty in making the 3 twist, they were down to 1 twist and decided on 3 twist...so if ya wanted to see what it's about, ya pretty much had to use a crummy barrel...check out the early reviews...where guys state I can't see through it, it looks fuzzy. It's not just one barrel it was all early barrels... and today's are probably not much better... I wasn't expecting much, and didn't get much, from previous reviews..
Did you're barrel look similar to this?

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Your first two pic's are damage to the rifling from when the button was pulled thru. Button rifling with these really fast twist I feel will always be an issue. Button rifling displaces the material it doesn't remove the material. Depending on the spec of the button and the material as it will always change they might be pulling a .341" to .342" button size for the groove down the barrel in order to end up with a .338" groove size. Like a snake swallowing a mouse. The steel will expand and spring back where we physically cut the grooves. Those edges of the lands is what we call tearing/tore. It could be a soft spot or a hard spot in the material and with that really fast twist and the conventional rifling it's tearing/breaking chunks out of the edges.

When we cut rifle the barrels we are only cutting like .0001" per pass. Basically shaving.

Also that hard edge of conventional rifling isn't going to help with the button process. That hard sharp edge is going to take a beating.

Your 3rd picture those are bore reamer marks (assuming they are reaming the bores before pulling the button thru as some shops/gun makers to save time and money will go from drilling the blank to just pulling a button thru but those look like bore reamer marks) on the lands and in the grooves. Again button rifling displaces material and the rougher that finish is from the bore reamer... the button is just going to push them down into the grooves as well.

Again the rougher bore/grooves like that and any damage to the edges of the lands.... means the bullets will take more of a beating/get damaged done to them and then the really fast twist rate isn't going to help anything at all either. Accuracy will suffer and bullets blowing up will be another.

That hard edge of conventional rifling will also leave a burr on the sides of the bullets. It will look like a flag sticking up on the side of the jacket. I've seen those burrs as big as a 1/32" of an inch and that will affect the bc of the bullet and affect the flight of the bullet as well.

Later, Frank
Bartlein Barrels
 
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That hard edge of conventional rifling will also leave a burr on the sides of the bullets. It will look like a flag sticking up on the side of the jacket.
I managed to recover a bullet shoot from the barrel where the pictures was taken. It shows signs of what you describes. It has also lost some weigh which probably is shaved off by the lands?
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Yes, typical Faxon 3 twist, mine was maybe worse...chunks of metal were torn off the rifling. Appeared fuzzy looking down the bore, ran a patch through it, and it was brown with slivers and small pieces of metal from the bore...So I lapped it before I shot it.. it still had chunks of metal missing in the beginning by the chamber, but was better toward the muzzle.
I ordered a new .338 6.5 twist barrel and have a chamber reamer, for a 2nd try before giving up on 8.6 Blackout.