8.6 Blk reloading info
- Thread starter unclemoak
- Start date
I guessing on the bullet....you mean, the little AR 15 338 ARC Imp running over 3700 fps... the bullet is a 9mm 50 grain copper, re-machine in a lathe collet to .338"... also used in AR 15 9 mm 16" at 2640 fps, and high velocity 358 win loads.
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Try experimenting with slow, heavy projectiles. I did this with 6.5 CM before the hybrids were even a thing. I pushed a 150 projectile somewhere around 2450 fps out of a 16” gun. It went transonic around 900 and had better performance in the wind than lighter, faster projectiles pushing above 2600 fps. Plenty of people are putting down all kinds of animals with a similar set up in 8.6, including hogs.
I built a 6 lb 308 AR 10 16" barrel, titanium, carbon fiber, magnesium upper.
It's lighter than my AR 15s.
It does 2442 fps with 208 ELDM.
Beats carrying a heavy AR 10 in 8.6 Blkout for range and potential killing power.
155 gr 2875 fps with Sierra Palma.
168 ELDM, 2756 fps.
308 sub moa, cheap to shoot, huge variety of bullets, magazines, etc.
The 8.6 Blk is mainly a sub gun...thats why most buy it...it has little range potential with supers and the 3 twist. Poor BCs at low velocity.
I increased it super potential with 6.5 twist running 200 grs to 2600 fps in 24" bolt gun.
High velocity kills alot better for general use.
The standard 308 put more energy on target with supers, cause it has more powder capacity and new bullets with good BC for any reasonable range for hunting hog or other game.
My 16" 308 AR has 1200 yd upper turrent dial if needed 168 eldm at 2756 fps to go long for targets...not game.
It's lighter than my AR 15s.
It does 2442 fps with 208 ELDM.
Beats carrying a heavy AR 10 in 8.6 Blkout for range and potential killing power.
155 gr 2875 fps with Sierra Palma.
168 ELDM, 2756 fps.
308 sub moa, cheap to shoot, huge variety of bullets, magazines, etc.
The 8.6 Blk is mainly a sub gun...thats why most buy it...it has little range potential with supers and the 3 twist. Poor BCs at low velocity.
I increased it super potential with 6.5 twist running 200 grs to 2600 fps in 24" bolt gun.
High velocity kills alot better for general use.
The standard 308 put more energy on target with supers, cause it has more powder capacity and new bullets with good BC for any reasonable range for hunting hog or other game.
My 16" 308 AR has 1200 yd upper turrent dial if needed 168 eldm at 2756 fps to go long for targets...not game.
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The gas system is is pretty much tied to the barrel length.... with a few variations for specific purposes that allow for a bit of overlap.
What barrel length, how you intend to shoot that barrel, ...mostly subs? suppressed? Supers only? Adjustable gas block?
All this, helps determine the best gas system for you.
There are a lot of good barrel makers mentioned in these pages ...
No, Faxon the worst, No, BA.
No, 3 twist.. poor results with these from personal experience.
Start with 5 twist mostly subs to 6.5 twist best for dual purpose and accurate for best results with 8.6 Blk.
For subs only I do not even recommend the 8.6 Blkout . The 338 Spectre is super accurate with subs and supers of limited velocity. The 338 ARC imp has good sub accuracy and 8.6 super velocity when comparing 12 to 16 inch barrels ..
Plus it's a handy light AR 15!
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So, I tried my hand at resizing the 277 Fury to 308 Win......the issue I am having is that I cannot get the last section (the steel) to size down in my rcbs full length die. Anyone else had any issues?
No issues...the steel portion does not size down it's already slightly undersize for all chambers, that use standard 308 case heads....as all the cases you'd make out of the 6.8x51 hybrid case have the same basic head size.
Unless the case heads are oversize, & Ive never had one that was.
Do not use a Small base FL resizing die. Even though they too should have a bit of clearance on the steel.
Try a different FL 308 sizeing die .... a cheap Lee FL die, they work and are cheap to replace when sizing hybrid cases.
6.8x51 to 308 is the easiest to make. I mandrel up the neck to .308, then use the 308 FL sizing die.
Unless the case heads are oversize, & Ive never had one that was.
Do not use a Small base FL resizing die. Even though they too should have a bit of clearance on the steel.
Try a different FL 308 sizeing die .... a cheap Lee FL die, they work and are cheap to replace when sizing hybrid cases.
6.8x51 to 308 is the easiest to make. I mandrel up the neck to .308, then use the 308 FL sizing die.
I’m rethinking my subsonic 338 project. After my dogshit 3tw experience.
Do you think that an unmodified Rex 350gr bullet would fit a normal 338ARC prefit at 2.500-2.600 in a normal chamber ?
I’m about to order a 12.5in barrel for a dedicated subsonic bolt gun off a ARC CDG action but I can’t get over the fact that the 8.6BLK case is way too big for good consistent ignition and we don’t have any good bulky powder in the N110 burn range.
I have a spare Grendel bolt head for my action so I wouldn’t be too hard to sell my alpha 86 brass I previously bought and go with the 338 arc for the “cheap” factory ammo for plinking and just shoot the Rex 350 loaded at max AICS coal.
Quick load gives me 1111FPS at 2.500 with 10.5gr N110 and that’s a 99% case fill and 50K psi. In my experience with long range subsonic this is a way more optimal configuration than the 55% burn you’d get with 86BLK.
I’d go with a preferred barrel in 6tw
The 6 or 6.5 twist is the way to go with the 338 ARC.
If you are running a bolt gun you can extend the throat for longer COAL to give the 350 gr Maker more powder capacity and close to 100% case fill. The 350 is a lot of bullet for the 338 ARC ...but if throsted or bore riders incorporated you can run it to 1200 fps if ya want...putting more energy on target that the 3 twist 8.6 blkout cause it's limited to 1050 fps max or it may come apart before it reaches the target.
If suppressed the 3 twist should be held to 900 fps ....but the 6.5 twist will run them as fast as the little case
The first 350 Makers were slow unmodified and mag length for AR 15...no room left for powder.
The 350 gr bore rider is very consistent and accurate in 338 Spectre (10 mag case) and slighty larger 338 ARC case. They may look ridiculous but it works without throating the barrel for just one bullet.
I shoot supers in mine mostly, but subs are fun. And for accurate supers and subs the tiny cases rule...although the supers are not very fast, they are accurate.
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Yes, for me changing from the 3 twist to the 6.5 twist made a huge difference in accuracy and higher velocities.
Plus you can run every bullet even cheap jacked lead as fast as the case will allow without fear of the bullet blowing up and destroying your muzzle devices.
The 350 Maker will not be limited to 1050 fps max as with the 3 twist...
Here the 350 Maker hits 1800 fps in a 6.5 twist barrel and doesn't blow up inside the muzzle device but gets to the target.
Large bullet fragments found in the dirt...
If you ran a can in a 3 twist you should limit the 350 maker to around 900 to 950 fps to make sure it doesn't destroy your silencer.
With the 6.5 twist double the velocity no problem, and go from 700 ft/lbs at 950 fps to over 2500 ft/ lbs at 1800 fps ...if ya want, and better accuracy.
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Yes it was a bad idea ...plus an expensive lesson for me...my curiosity was actually a dangerous endeavor with the 3 twist.
The ridiculous 3 twist barrel was taken off and scrapped as a really bad idea..which I kinda suppected all along....but I had to try it, to find out for myself.
...But "never again!"...I totally agree with that statement.
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