RABAZ
Active Member
no adjustable gas block - maybe that's the fix....
AR10 - can 6.5CM and 308Win uppers use same lower (buffer/spring)?
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Have three, 6.5 Creedmoor with 20" SS fluted barrel, 308 with 18" barrel, and a 45 Raptor with a 16" barrel. All use the same lower. And everyone required fine tuning the magazines. All my mags are now steel as it was much easier to tweak the edges, the 308 the easiest, the Raptor the most difficult. Color coded with wax pencils as they don't interchange. Even had to temper the Raptor mags so they were quite a bit stiffer. Hope that helps.
The outfit that makes your BCG can have quite an influence on how reliable these 308 rifles run. It is 16oz chunk of Tool steel, precision machine work , heat treatment,and coatings. Invest in the best. Aero has that nukpruff, Nickel Boron and two other levels of finish, all good. More than a few these outfits, sellN stuff , for around a hundred bucks, got a finish like horse shoe, right off the forge, pretty rough. Guys wonder why they won't run right. Good luck
buckbrush
Well-Known Member
Definitely sounds overgassed causing issues brcfo described. An adjustable gas block would be the first and likely best fix. 4 o'clock is about where you want the brass to end up.
brcfo_outdoors
Well-Known Member
Adjustable gas block or a heavier buffer when shooting 6.5 is definitely where I would start. The latter might be easier to tune and play with depending on how the existing gas block is attached.
buckbrush
Well-Known Member
Are you shooting factory ammo? If you're handloading, try some loads on the lowest safe end of the pressure scale. That may be something to try prior to throwing parts at it.
I've fired thousands of rounds through a number of suppressed 6.5 large frame gas guns and have bought all of the parts. What I determined was that they like low pressure more than anything.
I've fired thousands of rounds through a number of suppressed 6.5 large frame gas guns and have bought all of the parts. What I determined was that they like low pressure more than anything.
RABAZ
Active Member
Thanks - I do hand load. I'll back it off a bit and see if it gets happier!Are you shooting factory ammo? If you're handloading, try some loads on the lowest safe end of the pressure scale. That may be something to try prior to throwing parts at it.
I've fired thousands of rounds through a number of suppressed 6.5 large frame gas guns and have bought all of the parts. What I determined was that they like low pressure more than anything.
MarkAnthony
Well-Known Member
From the OP:
"with the 6.5CM: either failure to fully lock into battery, or failure to eject properly and getting jammed w subsequent round. Also, sometimes is prone to not locking back w an empty mag."
If the bcg does not lock back on an empty magazine when a single round is fired, it would seem that it is not getting enough gas to cycle or the buffer/spring combination is providing too much resistance. If it's the same buffer/spring combination as you are using for the 308 upper, then I would check gas port alignment between the gas block and barrel gas port. Checking to see if the bolt locks back on a single round is the first test on a new AR setup.
"with the 6.5CM: either failure to fully lock into battery, or failure to eject properly and getting jammed w subsequent round. Also, sometimes is prone to not locking back w an empty mag."
If the bcg does not lock back on an empty magazine when a single round is fired, it would seem that it is not getting enough gas to cycle or the buffer/spring combination is providing too much resistance. If it's the same buffer/spring combination as you are using for the 308 upper, then I would check gas port alignment between the gas block and barrel gas port. Checking to see if the bolt locks back on a single round is the first test on a new AR setup.
buckbrush
Well-Known Member
This may be occurring also. But, overgassing can cause the entire BCG to bottom out and bounce off of the rear of the buffer assembly and close before it is able to grab another round and before the bolt stop lever can do its job.
What does the rim of your cases look like? Is there a defined "notch" from the extractor? If so, I'm even more confident you would benefit from an adjustable gas block. I've got a 0.750" Superlative Arms block collecting dust. I'd be happy to send to you to try if it would work on your barrel and you decide that's what the issue may be.
M1A1ABRAMS
Well-Known Member
Do yourself a favor & watch this guys channel. He has a long playlist. And is the best I have seen. And doesn't live far from me.
You may find what you're looking for on his playlist. But your knowledge on how a AR works will grow vastly. If you can retain the info he provides.
If you really want to learn about an AR ? Go to youtube & look for "School of the American Rifle".
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RABAZ
Active Member
Thanks for the info and the offer. Let me try a couple things first and see how that works. Will advise. Not sure how to tell if your gas block will fit - I've got a heavy 22" barrel from Moriarti - I'll ck diameter of existing block.
RABAZ
Active Member
I will do so - love to soak up that info.
Your suggestion got me thinking. Found a video about the need to fine tune new mags always. The other guy spoke about getting a custom made follower for a specific caliber too. (.224 Valkyrie) They also addressed using a camera to carefully inspect how the mag fed rounds, looking for problems. Going to look for anyone making a 6.5 Creedmoor follower. Another video was a former Navy Seal who warned at the beginning that AR10's are not as interchangeable as AR15's
RABAZ
Active Member
Thanks for info; really for ALL of you who have responded. Very much appreciated!
