Ar-10 malfunctioning

[et_miller_87]

Hey guys, so I'm having a problem with my ar and its driving me nuts. Its been something that has been happening pretty much since I unboxed it. Stupid me didn't sent it back and say fix it. Not sure if they will at this point. Anyhow, its a palmetto state arms basic ar10. No upgrades as far as operating components. What's happening is the bolt fails to go into battery. At the range yesterday, I lost count how many times it failed. I shot 100 rounds, loading 10 at a time. 9/10 first round chambering it failed to go into battery. Where I lost count was when the second or third round of a magazine failed to go into battery. This has happened on factory ammo just as often as my reloads. Using the forward assist doesnt help. It will not go anymore forward. This is my first 21st, but am fairly familiar with components anf the operation of the actions. Does anyone have anything I might check that jumps out at them?

Some things I have looked at so far are the ejection plunger and ejector, both move freely when pushed upon. Without a. Cartdridge I can watch the bolt go into battery and evrything moves freely within the receiver.

Kinda scratching my head at this point! Any and all suggestion is welcomed and greatly appreciated

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[et_miller_87]

Did some research and may have answered my own questions. Probably should have done that before being lazy and just asking. So ill share what I found, so i can possibly help someone else who may have my same problems.

Its a common problem for the PA10 to fail to go into battery. Why? Because of a few reasons. Least worrisome to most:
1. Wrong buffer spring. Apparently, in haste to get the highly proprietary rifle to the market, the wrong buffer spring was installed on some rifles. Supposedly, the buffer spring for. 223 was commonly and by mistake installed in the 308. How that large of a mistake happens, couldn't tell you. This problem I'm seeing is less common than others, and was only found through some digging and can't verify the validity of it, but was a common enough complaint to at least acknowledge its possibility.
2. Extractor spring is too heavy and stiff. This would explain why my fired cases are becoming damaged, disformed and basically shaved where the extractor mated with my cartridge for those that did fire. All to often did my weapon fail to go into battery because the cartridge did not seat all the way on the bolt past the extractor. I had suspicions of this but couldn't verify its validity until countless other accounts of the same thing confirmed my thoughts. Now it makes sense.
3. Chamber tolerances are too tight. This concerns me the most. Is it failing to go into battery because its simply too tight? Concerns of overpressure come to mind. I'm only using homeloaded ammunition so I know the cases are the correct dimensions. My previously loaded rounds were a COL of 2.800 with 150 btfmj rounds. The load data suggested the COL of 2.8 and I went with that as a base. Deep grooves in the unfired, failure to seat rounds told me they were way too long for that rifle. New recipe, same bullet, different powder suggest 2.700 COL and still found light grooves on the bullet on some that failed to go into battery.

I still feel the ejector is the main culprit after research, but am still concerned about the chamber. Contacted PSA and hope to hear from them soon.

I've read many fellow PA10 owners claim that swapping the stiff PSA 308 bcg ejector spring with a more common 223 spring seems to be the fix. I may give that a whirl and see how it works.

Sorry for the long winded finding, but hope it helps someone else. Again, all of the common occurring problems listed are what I found in my digging and not verified by myself yet. Happy shooting fellas.

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[et_miller_87]

Well. Tried a couple of different springs. Failure to feed isn't a problem anymore. Now its failure to eject the spent cartridge. Re installed original spring and oring and it no longer fails to feed. But it continues to fail to eject. Plunger and extractor both move freely as they should. Extractor is still quite stiff with original spring but moves. Anybody have further suggestions to check or try? Btw, palmetto state has still yet to respond to my emails.

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[salmonchaser]

You tried a couple of different springs on the extractor, have you replaced the extractor itself?


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[et_miller_87]

No i haven't. From what I have inspected, there is minimal wear on the extractor itself. It is definitely worth a shot to replace it though.

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[salmonchaser]

Understood, we had fifty or sixty AR's at my old department, only replaced a couple during my tenure as armorer. Did see a couple of rough chambers also create problems. I've been looking for my old armory manuals but can't come up with them.
I've replaced quite a few on Glocks but the damage was always obvious.
Interesting is the number of problems I've run into with Remington 1187 and 870 shotguns. I've actually put together a kit so I can fix my clients gun at lunch. I bet this year I've replaced half dozen extractors and replaced the O rings on 1/2 dozen 1100s.
My point being, on the shotguns I really couldn't see anything wrong, just worn enough to not work every time.


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[et_miller_87]

That I could most definitely understand failure to eject if it were super worn. Thus rifle has probably less than 500 rounds through it. None were heavy loads. Its never shot anything over 150 grain bullet. So I don't think its endured enough to wear it out or damage it really.

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[Ridgerunner665]

A picture of the bolt face?

From the front and sides.

Take a Scotch Brite pad to the sides of the extractor and the channel it rides in.

 

[salmonchaser]

I guess I was thinking more along the lines of quality control, or the lack thereof you mentioned. Perhaps it doesn't quite meet specs.


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[et_miller_87]

Here's a couple of shots of the bolt and extractor.

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[Ridgerunner665]

Nothing is jumping out at me...

Working the bolt carrier group in and out of battery by hand....

Does anything feel like its catching, as in the bolt not rotating as is should?

A little Scotch Brite to the parts I mentioned couldn't hurt.

 

[et_miller_87]

No round being chambered and it operates smooth as silk. No binds and goes into battery perfectly. Now that I tinkered with it, it'll chamber a round but won't eject it now. Its stupid and annoying. I'm going to clean it again and polish the moving parts and see what happens.

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[Ridgerunner665]

If the polish doesn't fix it get a new extractor.

 

[et_miller_87]

Notice the gouging? Several of the teeth have it on the back side as well. Theres only one thing that u kniw if that will cause that.

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[et_miller_87]

I meant to ask, because I don't know. But, what is the torque value for the barrel nut on an ar-10? I recall for an ar-15 being in the realm of 80 ft-lb. But mine was barely hand tight. I'm pretty positive that was not correct.

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[Ridgerunner665]

There is no torque "spec" on AR's...just a torque "range"...for a 15, its 30-80 ft lbs....for a 10 its 45-90 ft lbs.

Remember to torque to at least 30-45 lbs, loosen it, torque it to 30-45 lbs., loosen it torque it 30-45 lbs....then get the alignment right, with no less than 45 ft. lbs of torque, but no more than 90.

If you can't make it work, get a new barrel nut, or if you're comfy doing it, shave a little off the face and try again.

 

[et_miller_87]

Yes, I knew there was a range. Even at 30 ft lbs, I dont believe I would be able to unthread it with as little effort as it took. It was hardly hand tight. I purchased this weapon ready to fire, did not build it, nor have I disassembled the barrel from the upper before. It should not have been that loose to begin with

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[Ridgerunner665]

Nope, you wouldn't...sounds like maybe that one was just ran up on there once and torqued without ever stretching the threads.

Or maybe never even torqued at all...

 

[et_miller_87]

With the quality assurance or lack there of I wouldnt be surprised to hear someone forgot to torque it

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[salmonchaser]

Well it will be interesting to see if the rifle starts to function reliably with the barrel screwed on correctly.


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