PA 10 (AR-10) jamming after first shot.

[GARD72977]

I bought a PA 10 some time ago and just got around to shooting it today. Its jamming after the first shot. Cartridge is really stuck and bolt is out of battery. Foward asst didnt close the bolt. The cartridge was hard to extract. ( once after FWD ASST and once without.

I have read about heavy extractor springs causing problems. This seems more like the cartridge is not sized enough.

Im going to try some factory rounds next weekend. Im a little confused because when you release the bolt the first round feeds fine.

Extracted cartridge has no rifling engraved on bullet. One cartridge had some scuff marks on case.

Anyone else have this problem.

[Hannibal]

If I read your post correctly, these are reloads you're having problems with? Is the fired case stuck,or is the next round not chambering fully? Have you tried cycling a magazine full of rounds thru to see if they chamber and extract correctly? If these are, in fact, reloads, try some factory ammo and see if they function correctly.

[oldblinddog]

It needs to be lubricated. You just got around to shooting a new rifle. Did you lube the bolt carrier group before shooting? I ask from experience.

http://www.rifleshootermag.com/rifles/ar-15/ar-lube-advice-from-the-experts/
https://www.ar15.com/forums/ar-15/-/7-548967/?

[Artful]

Other questions...
Did you try more than one Magazine?
Is it always jamming when feeding from one side (left or right feed jams)
When it jams you say the round doesn't always go into battery
- did you try single feed from magazine with the round that jammed?
- did you try multiple times with just one round in the magazine?
- if that worked then did you load two rounds in the magazine, and try it that way or is it always a full magazine?
(Some times my magazines like less than the max load out)
And yes try some factory ammo - that is a good idea

[Tripplebeards]

Try some slip 2000 lube or similar and try another mag if you have one. Some guns are picky and won't cycle low pressure/velocity rounds. Had a bushmaster that use to do that all the time. I fixed the problem by selling it and replaced it with a POF. It cycles everything, dry and dirty.

[GARD72977]

I did not lube the bolt. These are reloads. I only have P-mags that came with RPR.

I will take some factory rounds next weekend. I ordered a couple Brownell mags last night.

My guess right now is bolt is dry. Makes me fell pretty stupid but happy at the same time.

[bruce drake]

I own a PA10 and I had to go back and recheck my sizing die setup on my reloads as I was having problems almost the same as you. The bullets would feed in my 308 Bolt rifles but not in the AR. I went back and determined that the PA10's barrel chamber was tighter than my military surplus rifles and I was shooting reloads that I had used in those rifles. When I fired factory loads in the PA10, no problem. It was my reloads. So I went back in and resized the brass with a small base sizer die and my issues with cartridges not fully seating went away.
https://www.midwayusa.com/product/597261/rcbs-small-base-sizer-die

[2ndAmendmentNut]

I usually wet my AR bolts with CLP and lightly grease the rails. Leave the forward assist alone, if you really do have a chambering issue the FA will only make it worse. Try shooting a single round with an empty mag. If the bolt fails to lock open you might have a short stroke problem. Short stroking is usually caused by one of three things. 1) Weak or light ammo. 2) A heavy spring or buffer. 3) Not enough gas.

I should point out that not enough gas is rarely the problem in my experience. If the gas block is properly aligned over the hole most ARs are grossly over gassed and benefit from either a heavier spring and buffer, or an adjustable gas block. As a reloader I prefer the adjustable gas block route.


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[seaboltm]

At 10s can be picky about gas, especially with shorter barrels. An adjustable gas block solves the problem. Also note too much gas can mimic too little gas.

[trapper9260]

Also I found in my AR 10 is that with reload what data you are usen. It might fire the firs shot but after that do like OP stated. beside the lube thing I had also. I had some NATO ammo that did what was stated and found out that lot number was a bad batch. Now I have it all work fine.My is a DPMS LR 308.Also I use the not only the small base die but also the LFC it took care of the problem also.This is what I found with the time I spent to take care of the problem I had. Also there is the style of the nose of the boolit also for it to feed also.

[sawinredneck]

Sorry, you didn’t provide much information so this is just throwing things to see what sticks! I also have a DPMS .308. Upon break in you need to use factory ammo, even cheap ball is fine, and you want it ET! Almost oil dripping off wet! I honestly don’t think you can get them too wet! Then put around 100rds through it getting it sighted in and nutting around. Then clean it good and lube it normally. These come tight from the factory and need to wear in.
If you are reloading with cast I can about garuntte your OAL is too long! Chambers on these are tight! My gun did the exact same as yours when I started out with cast, first round was fine, then nothing! I ended up sizing a case, sticking a bullet in and chamfering it. After extraction I measured the OAL and used that for my length. (Try it a few times to get an average.)
My thoughts on the forward assist, if the .308 doesn’t create enough energy on recoil to chamber, I’m not pushing it in with my thumb! I bought a flat sided Sportical as I had no need/want for the dust cover or fwd assist.
I can just about assure you the bullets are catching on the leade of the rifeling and that’s why the bolt won’t close. Either shorten your OAL or get it throated.

[GARD72977]

My loads are LC 74 brass with 42.5gr 4895 150gr fmj. These are near max loads.

[10-x]

Had the same problem. Carefully ran a reamer in chamber after marking a GI ball cartridge with blueing and chambering it, showed tight chamber, so 2/3 rds turn of reamer and OK. Heard several others with PSA rifles with same problem. Friend has a 9 mm that looks to be tight. Checking it and most likely will send it back.

[sawinredneck]

My loads are LC 74 brass with 42.5gr 4895 150gr fmj. These are near max loads.

Ok, are you full length sizing these cases? A small base die may or may not help, but with semiauto you need to full length size them.
What is your OAL? As I said, these are throated tight, even .020” off can create an issue! Check the OAL from several sources. Also drop the load down, this will allow wiggle room while getting your chamfering length right. As others have said, you may have overshot your accuracy load as well.
Get a Lee collet crimp die, these guns have a bit of recoil and maybe the first round was fine on OAL but the recoil caused the next bullet to “jump” a bit causing the bolt not to close?
Seriously, these guns are tight in every way manageable, you have to make rounds to fit it, or modify the gun to work with your loads.
Hope something here helps.

[Digger]

Seems the most common is "tight chamber" ....as others have said here .
Love all the info that everyone has for input , good advise.
Also have a AR-10 , brand new , did the exact same thing , was thinking the chamber reamer ?
found some where a gentleman mentioned " Chrome polish the chamber and full length size"
Result ? ,, One happy camper here , functions fine now and eats up all my reloads.
found some chrome polish and used a cotton shotgun swab and it all came together.
Have been using my 308 reloads in my Ruger bolt and my garand tanker with no problems until the AR came along , now we are one happy family .

[Bubba w/a 45/70]

If you keep on having problems, check out https://forum.308ar.com/ as those guys have more knowledge on getting 308AR's to run, and run correctly, than anyone.

But basics first,seriously wet on the lube until broken in.
Factory ammo for break-in is best.
And technical questions can be answered easily, along with well vetted suggestions on parts to purchase if needed.....by a group of hard core 308AR nuts.

[55fairlane]

Ok, are you full length sizing these cases? A small base die may or may not help, but with semiauto you need to full length size them.
What is your OAL? As I said, these are throated tight, even .020” off can create an issue! Check the OAL from several sources. Also drop the load down, this will allow wiggle room while getting your chamfering length right. As others have said, you may have overshot your accuracy load as well.
Get a Lee collet crimp die, these guns have a bit of recoil and maybe the first round was fine on OAL but the recoil caused the next bullet to “jump” a bit causing the bolt not to close?
Seriously, these guns are tight in every way manageable, you have to make rounds to fit it, or modify the gun to work with your loads.
Hope something here helps.

This.....had a guy at our club with similar problems.....must full leant resize, I trim mine .003 under minimum.....run bolt wet....not greased, but wet with oil.....

Try with factory loads, crono them, check your hand loads, powder might be a little fast burning......

My .02 cents

Aaron

[gnostic]

Small base dies will make your problems will go away...

[sawinredneck]

Small base dies will make your problems will go away...

Not if his OAL is catching the ogive of the bullet in the tight chamber. I had to shorten my OAL by .100” to get my Lee 170grn RN cast to chamber.

[GARD72977]

Hey guys I wanted to give an update on the problem. It seems the bolt just needed some oil. Its been back to the range and ran 25rds without a problem.

[sawinredneck]

Glad to hear you got it sorted out.

[Love Life]

Run AR rifles wet.


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