Help needed with AR

[JASON50CAL]

Ok so I just got a 10.5” upper chambered in 7.62x39 and I’m having issues with it. It’s a factory upper and not a build. I have tried brass and steel cased ammo and it does the same thing. First It won’t extract a fired round, I have found out that the extractor isn’t going ove the rim. I can see a shiny spot on the rim where the extractor just goes up onto the side of the rim but won’t go over it to grip the case to extract it. Second it won’t lock back on an empty mag if I load a single round into it so it’s under gassed I’m assuming. I tried turning the gas block slightly but no change. Guessing I may have to drill the gas port out slightly. Anyone have any ideas how I can fix the extractor issue first?

 

[tobnpr]

Pull the bolt and try to snap the extractor over the rim, see how much difficulty is involved.
I had to remove a rubber O-ring that came with a 6.5 Grendel extractor for the same reason.
Too much force required to compress the O-ring (I have no idea why it was there in the first place- it's not needed) enough for the extractor to snap over the rim. Gun ran flawlessly after it was removed.

No idea if it's related to your problem, but symptoms are identical. Finally realized the force from the buffer tube just wasn't enough- and this solved it without getting into a heavier buffer spring.

 

[gunsandgunsmithing]

If it's short stroking, fixing that may well fix the extractor issue. Check that the gas ports in the block and bbl are perfectly aligned first. Fix one problem at a time. Once it's locking back, if it still has an extractor problem, fix that. The rubber oring is there to prevent extractor problems but it does take some force to compress it. Some extractors need some minor work on the edges to work with that diameter case. I suspect this but I'd make sure everything else is right first.

 

[JASON50CAL]

Pull the bolt and try to snap the extractor over the rim, see how much difficulty is involved.
I had to remove a rubber O-ring that came with a 6.5 Grendel extractor for the same reason.
Too much force required to compress the O-ring (I have no idea why it was there in the first place- it's not needed) enough for the extractor to snap over the rim. Gun ran flawlessly after it was removed.

No idea if it's related to your problem, but symptoms are identical. Finally realized the force from the buffer tube just wasn't enough- and this solved it without getting into a heavier buffer spring.

I removed it already as it seemed to have a lot of tension on it but it didn’t change anything

 

[JASON50CAL]

If it's short stroking, fixing that may well fix the extractor issue. Check that the gas ports in the block and bbl are perfectly aligned first. Fix one problem at a time. Once it's locking back, if it still has an extractor problem, fix that. The rubber oring is there to prevent extractor problems but it does take some force to compress it. Some extractors need some minor work on the edges to work with that diameter case. I suspect this but I'd make sure everything else is right first.

I’ll check that and see if I can verify it with my bore scope as well

 

[PigButtons]

What does a spent case look like? Is there any chance that the head space it not set properly and therefore the extractor can't get far enough forward to get past the rim. That may cause the round to move rearward early and never build enough pressure in the barrel to get the bolt fully to the rear. If the case looks scorched more than normal down the sides this may be your problem.

 

[marazzi59]

Don't assume it's under gassed. It very well could be over gassed and sometimes the they look alike

 

[Ggmac]

Have you disassembled the bolt , if not do so and make sure the gas rings are installed properly. Not a big gas loss but every bit helps .

 

[JASON50CAL]

What does a spent case look like? Is there any chance that the head space it not set properly and therefore the extractor can't get far enough forward to get past the rim. That may cause the round to move rearward early and never build enough pressure in the barrel to get the bolt fully to the rear. If the case looks scorched more than normal down the sides this may be your problem.

Cases aren’t scorched at all. I wondered if this could be the problem as well since it seems like the bolt goes all the way home but the extractor doesn’t appear to be going all the way over the rim

 

[JASON50CAL]

Have you disassembled the bolt , if not do so and make sure the gas rings are installed properly. Not a big gas loss but every bit helps .

I have disassembled the bolt several times and cleaned everything. I’ll check the gas rings

 

[rockrat]

Could it be a type II bolt from a 6.5grendel with the deeper boltface, instead of a type I? Just throwing that out as it probably wouldn't fire with the wrong bolt.

 

[JASON50CAL]

Well I finally have it fixed. I had a bolt for a 6.8 that I wasn’t using so I took the extractor and put it on my 7.62 bolt and it ran great except for didn’t pick up one round from the mag for some reason.