AR10 problem cycling

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dtalley

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After building several AR15's with no problems, I decided to build an AR10. Purchased stripped upper and stripped lower and bolt carrier group from PSA. Barrel and parts kit from Surplus Ammo. Went to test fire and first two rounds where fine. Pulled the trigger on the 3rd round and it stove piped. Cleared it closed the bolt and it didn't stove pipe but didn't go al the way into battery. Forward assist didn't help. Tried to eject the round and bolt was stuck. Got it cleared with some work and very next shot did the same thing. Pulled the gun apart and figured it was too dry. Pulled the BCG apart cleaned real good lubed real good and it cycle a little better but still jammed up. Noticed it was really jacking the rounds up. Used to different PMags.

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Anyone got an idea where I should look next?
 
My AR-10 type rifle doesn't have a forward assist. I have been advised that using one on a .308 will jam the case most every time. I know that doesn't help your problem, but just sayin'... Good Luck.
 
Are you using factory ammo or reloads? From your description the bolt is not fully closing on your rounds? And then it takes a lot of work to extract that round? Could it be that your ammo is out of spec, won't close on a tight chamber?

I had a DPMS AR10. I had some ammo out of spec. The bolt would almost close and the forward assist wouldn't help. It was super hard to extract the round. Found out the ammo was out of spec. Wouldn't feed in the bolt gun either. The FAL loved the stuff.
 
I used 3 different Brands of Ammo, Hornady 168gr A-Max Superformance, Hornady American Whitetail 150gr and Federal Fusion 150gr. First round off the Magazine was flawless it is the next round that always drags and hangs up. It almost seems like the magazine is pushing the rounds up to close to the bolt or something. I am going to try and polish the underside of the BCG and see what happens. Got to stop and get some snapcaps first, tired of boogering up good rounds.
 
Try the plonk test. That was the problem with mine. Separate the halves of the rifle, chamber a round and give it a firm (but not ridiculous) push to seat it fully in the chamber. Turn the upper "barrel up" and the round should drop out. If not, you have a tight chamber or tight throat. Push it out with a cleaning rod, mark the round up with a sharpie and chamber it by hand to see where the problem is.

Using 125s worked for me until throat erosion let me use 150s. The barrel manufacturer can fix it too.
 
Sounds like a magazine issue to me. That's always the simplest thing to start with and it's almost always the problem. Try different magazines and different brands of magazines.

I have a Rock River LAR-8 .308. It uses FAL magazines. I bought a bunch of cheap ones off the internet (I mean CHEAP too, like $7 each)... half of them work and the others do the same thing you're talking about. Nose up cartridges, jamming against the top of the chamber. When I use a quality magazine, the gun works great. I'd start with that.
 
Polish the chamber. it will work wonders. Take a 20ga brass brush and a piece of cleaning rod. chuck in drill and cover brush with Flitz. Then polish like crazy. clean and try.It did wonders for mine.
 
I was thinking about that also epwrangler. I finally got my hands on a ASC magazine and used some snap caps and it was better but still scratched the next round in line in the magazine. I'm thinking that I will polish the chamber and the bottom of the BCG and give it a try.

I am going to look for another brand magazine just for grins

Thanks for all the replies.
 
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