PA10 Chambering issues

[Sailormilan2]

I've got a PA10 that I have just finished putting together, and today, fired about 40 rounds through it.
The issue it has is that periodically it will jam on a loaded round, not fully going into battery. The hammer drops, but no mark will be on the primer. Sometimes I can pull the bolt open, but sometimes it requires a good smack with a block of wood/leather mallet. Sometimes a round that stuck once, can be put back in the mag and fired with no problems.
I suspect a tight chamber, and am trying decide the best way to deal with that. I have a pull through reamer in .308 I can use to very slightly enlarge the chamber.
To provide some answers to possible questions, the ammo today was Radway Green 7.62NATO, which is good quality stuff.
All the parts used are PSA parts, so there should be no issues caused by interchangability problems.

So, any suggestions?

[ar15barrels]

What's a PA10?

Check the headspace of the GUN.
Check the headspace of the AMMO.

It's common for 7.62x51 spec ammo to cause this problem in 308 spec chambers as 308 spec chambers can be 0.002" shorter than 7.62x51 spec chambers.
"Can be" does not mean they ARE, but that CAN be...
This is where incremental headspace gauges come into play...

[baih777]

Palmetto State Armory version AR in 308.

[Sailormilan2]

Well, after doing a bit of online research, I found that the PA10s have issues with chambering, often due to an overly heavy extractor spring. Several places stated they had a double spring, in the 8# range. Replacing the spring with an AR15 usually fixed the chambering issues. Testing my extractor, and it required heavy pressure to move it.
So, I took my bolt apart, and got the spring out. It was a heavy single spring, with a rubber "O" ring. Lacking an AR15 extractor spring, I used some spring stock of the same diameter coils, but slightly smaller wire diameter. I cut a piece, about 1 - 1 1/2 coils longer than the old spring, and installed that. Extrator seems to move a bit easier now.
I test the chamber with an unfired RG 7.62NATO round and a Nosler .308 round and bolt dropped into the chamber the same distance, and both required slight finger pressure to fully chamber them.
So, I am off the range tomorrow to test it out.

[Twystd1]

That is an interesting fix. I didn't know a over sprung extractor could do that.
I will be interested to hear if the new spring fixed the problem.

Please report back on your findings.

Thanks for the heads up.

-T

[ar15barrels]

That is an interesting fix. I didn't know a over sprung extractor could do that.
I will be interested to hear if the new spring fixed the problem.

Difficulty chambering from extractor spring tension will ONLY matter when you are HAND CYCLING the gun.
We know that the guns were only designed to be cycled under gas pressure though and there will be no problems with a REALLY heavy extractor spring at the carrier speeds attained under gas power.

The lighter extractor spring is likely to cause extraction problems under gas pressure.

[nodixe]

So any results? I have a pa10 on the way so was wondering....

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[kcstott]

Difficulty chambering from extractor spring tension will ONLY matter when you are HAND CYCLING the gun.
We know that the guns were only designed to be cycled under gas pressure though and there will be no problems with a REALLY heavy extractor spring at the carrier speeds attained under gas power.

The lighter extractor spring is likely to cause extraction problems under gas pressure.

But he read it on the internet so it must be true

[Sailormilan2]

So any results? I have a pa10 on the way so was wondering....

Sent from my SCH-I545 using Tapatalk

A quick range test was just done today. Very simple test the new extractor spring to see if that fixed the stuck case issue.
20 rds fired as fast as I could pull the trigger. No stuck cases, but it might now be a tad under sprung. I had one failure to eject, which may have been a case of the rim coming out from under the extractor.
So, I now have an AR15 spring on the way, which most reports seem to say works.
Now I can focus on an accuracy test.

[TATER313]

I have a PA10. No issues.

[Junkie]

I have an AR47 with a REALLY heavy extractor spring. I pretty much can't get it to chamber when riding the CH, even if I then smack the FA pretty well. However, it doesn't seem to have any problems when cycling. It has an insert with a solid core, REALLY stiff.

[vboy619]

+1 for extractor spring. i did that with my PA10 its works good.