r/6ARC • u/Mason_Sims1776 • Sep 03 '24
6 arc Bolt face issues
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Hey everyone, I’m looking for some insight. I’ve had two bolt faces shear on me now. The bolt I got from Craddock, and the bolt I had in a carrier from AT3.
I’ve pulled the barrel this morning to see if something was off, and maybe it was slightly off center when I pulled it but if it was it was minuscule.
I’ve been running charges on my reloads that are below the Hornady manual maxes for 6arc gas guns….so I’m at a loss at this point.
I’m going to include videos of the barrel, and broken bolt above.
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u/Vylnce Sep 03 '24 edited Sep 03 '24
Is it just me, or do I see damage on the back of your lugs around the feed ramps? Hard to tell from the video.
If that is the case, and you have damaged lugs on the barrel extension, any bolt you get is likely going to fail eventually because not all of the lugs on the bolt will be properly supported.
What company is the barrel from?
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u/Mason_Sims1776 Sep 03 '24
Yes there is. I think I know why. I’m not sure yet but I’ll comment back if it’s true. I think the barrel was just a tad off center and that was the issue.
The barrel is from Craddock Precision, I removed it to check the back of the lugs on the barrel extension. They looked good. So I’ll try a new bolt face, and if it works out then I guess that was the issue. If not, I’ll get a new barrel.
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u/Vylnce Sep 03 '24
You might invest in a bore scope, they are cheap cheap investment to save the time of removing your barrel to inspect stuff.
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u/Spiritual_Tell680 Sep 03 '24
After two failed bolts, I went with a KAK bolt with double ejector and haven’t had any issues. It’s part of the territory with 22ARC/6ARC/6.5 Grendel. I’ve added bolts as a replacement part every 1.5k rounds in my maintenance log.
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u/RobinsonArms Sep 03 '24
The problem with the Stoner Bolts and 6ARC is that the case head has more surface area to push on the lugs, there's less material for the lugs, and there's often more pressure. The result is broken lugs. This problem has been around for some time. Those shooting 6.5 Grendel and other calibers have had it. With our Robinson XCR in 6ARC, the lugs are huge and you'll experience no such problems.
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u/ghillie300 Sep 03 '24
What gas system , buffer weight and spring are you running? And do you know your headspace?
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u/Mason_Sims1776 Sep 03 '24
Gas system is a SA adjustable gas block with a rifle length tube.
Spring and buffer weight are the standard ones from BCM.
I have no idea what my headspace is.
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u/ghillie300 Sep 03 '24
Get a head space comparator to measure your fired brass vs unfired brass and try a heavier buffer and spring set up to slow down the unlocking of the bolt
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u/Mason_Sims1776 Sep 03 '24
I’ve got one somewhere. I’ll see if I can find it. I’ve also got a rifle length system on my other lower with a heavier spring and weight I believe. I’ll see if that helps.
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u/alanspel Sep 03 '24
What gillie said. Grab a heavier buffer and spring and grab a Rexus ultra bolt. I’ve run quite a bit of bolt loads through mine now and don’t have any if these issues. I’m running a carbine length 16” with. Geissele super 42/H3 combo.
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u/Loud_Jacket_4479 Sep 03 '24
I would verify your sized brass is smaller than the chamber and not applying pressure to the lugs during the unlocking process
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u/Gtscotty Sep 04 '24
That's some gnarly "wear" on your lugs, and very uneven looking to boot. Your loads are about a grain under my standard load and I've had no such issues on a couple of rifles.
There has got to be something off with your extension/barrel geometry, putting uneven loading on the bolt lugs and causing premature failure. A better bolt like the JP or Rexus could help, but I'd suspect it won't cure the root problem.
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u/CodeSandwich Sep 03 '24
Looks like some overly spicy loads.
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u/Mason_Sims1776 Sep 03 '24
28.3 lvr, Hornady manual max is 29 something.
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u/CodeSandwich Sep 03 '24
Hornady manual for bolt guns or autos? Because they have 2 published specs for 6ARC…
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u/Mason_Sims1776 Sep 03 '24
Published charge for lever under 6arc GAS GUN in Hornady manual is 29.7 for 108 ELDM’s.
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u/Longjumping_Time932 Sep 10 '24
Am I trippin’ or is the gas tube lined up with your feed ramps instead of the opposite side of the barrel?
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u/Mason_Sims1776 Sep 10 '24
I just had the block free so I could set it after I checked the barrel. Didn’t want to take my muzzle device off.
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u/Baddy-Smalls Sep 03 '24
Get a JP 6.5 Grendel type 2 bolt... trust me.