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Proof AR-10 Barrel - cycling issue

jrsandiego12

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Full Member
Minuteman
Feb 11, 2020
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San Diego, CA
I have a Proof AR-10 barrel (carbon fiber) in 6.5 CM, 24 inch length, rifle +2 gas port - with an SLR adjustable gas block. The Proof barrel has a .082 gas port.

Previously this gun had a 22" Ballistic Advantage barrel - and did not have any cycling issues.

With a LANTAC bolt, the Proof Barrel had occasional short-stroke jams, but I just chalked it up to random gas gun failure. I almost exclusively ran 140 grain factory ammi with this set-up.

But I recently upgraded the bolt to the JP Low mass BCG and high pressure bolt designed for the 6.5 Creed. And switched to the 130 grain Berger OTM bullet. With the original standard buffer that I was running with the LANTAC, the JP would not cycle at all - either completely failing to pick up a round or short-stroke jamming. Even with the gas port fully open, it was ejecting at the 5 o'clock. Switched to the JP Silent Capture Spring and it cycled for about 40 rounds and then went back to no cycling. Switched to the lightest weight spring and the 140s now cycle and lock back at empty, but the 130s cycle, but not lock back.

I suspect that this is a function of the Proof smaller port that they "optimized" for the 6.5 Creedmoor? A friends Kreiger has a .095 gas port and does not have this issue at all, running same bolt, but superlative adjustable gas block.

Anyone else run into this issue and solve it somehow??
 
Are you 100% positive the gas block is aligned? Have you put an empty cartridge in the chamber and blown air in the end of the barrel to check ample air flow?

If so, I would consider opening the port up to .095.
 
Just curious, between the two barrels, what was the difference in accuracy with the same ammo? I ask because my BA barrels are very accurate with 77gr SMK but I’m using a CF Proof on a .308 build.
 
Sounds under gassed or needs a lighter spring or buffer.

Also try lubing the shit out of it.
 
I would re-install the gas block(and inspect).see exactly what size the gas port is(it’s always possible it wasn’t drilled properly) before I did anything else, it’s possible a slighter smaller gas port could possibly cause short stoking but from what your describing it’s hardly getting any gas at all. Given Proof’s reputation I’m guessing their specs are right.
 
Loose gas block like suggested possibly. Also I had an LMT FA .223 BCG that just wouldn’t close all the time with a Seekins 300 blackout upper. Had the gas block tightened by Seekins and that helped some but still just didn’t work as good as the Seekins BCG. I feel Frankensteining these high end pieces together is risky. Others seem to feel the same way on here. Nevertheless I’m doing it again with a Proof barrel on Seekins AR10 🤣
 
Are you 100% positive the gas block is aligned? Have you put an empty cartridge in the chamber and blown air in the end of the barrel to check ample air flow?

If so, I would consider opening the port up to .095.

I think so, but will try this.
 
Just curious, between the two barrels, what was the difference in accuracy with the same ammo? I ask because my BA barrels are very accurate with 77gr SMK but I’m using a CF Proof on a .308 build.

My BA was very accurate as well across a range of ammo. I have found the Proof CF barrel to be as accurate, but it is a lot more fickle with the ammo or load it performs well with. I put a Proof CF 20" barrel on my 308 - and honestly have been disappointed in it. Proof did offer to have me send them the gun to check out why its not grouping well.
 
Loose gas block like suggested possibly. Also I had an LMT FA .223 BCG that just wouldn’t close all the time with a Seekins 300 blackout upper. Had the gas block tightened by Seekins and that helped some but still just didn’t work as good as the Seekins BCG. I feel Frankensteining these high end pieces together is risky. Others seem to feel the same way on here. Nevertheless I’m doing it again with a Proof barrel on Seekins AR10 🤣

I agree - its always something with gas guns that just seems a little incompatible.
 
My BA was very accurate as well across a range of ammo. I have found the Proof CF barrel to be as accurate, but it is a lot more fickle with the ammo or load it performs well with. I put a Proof CF 20" barrel on my 308 - and honestly have been disappointed in it. Proof did offer to have me send them the gun to check out why its not grouping well.
Interesting. Thanks for the feedback.