7.62x39 AR extraction issues

[turtlehead]

I'm having problems with cases not extracting. Still fully seated in the chamber.

Rifle has a 16" PSA barrel with mid-length gas. Chamber looks smooth and clean. Extractor looks fine. Have been using a Spike's ST-T2 buffer (4oz) with chrome silicon spring.

Any ideas? I have a carbine buffer (3oz) to try. Is it possible that would help?

Thanks!

[B-Shot]

What types of ammo does it happen with? I would try the other buffer and spring just to see if anything changes. A 762 bolt in a ar really needs a stout buffer spring. Have you disassembled the bolt completely and checked the extractor spring?

[turtlehead]

Red Army ammo. I have some Wolf to try.

Have not looked at the extractor spring. What should I be looking for?

[doofus47]

About what % is not extracting?

Do they start out okay and then you get more as you shoot more on any given day? Buildup of something or heating of something?

Do the extracted cases have scratches on them that can't be traced back to magazine feed lips? Burr in chamber?

If you pickup a cartridge onto the bolt, does it wiggle a bunch and want to fall off the bolt face: maybe a broken extractor/extractor spring.

My 1.5 c.

[ed308]

If the rifle is not cycling, check the gas system. If it cycles fine, check the extractor and extractor spring. I would also scrub and polish the chamber.

[smee78]

A lot or questions need to be answered,

1. How often is this happening? Always, after shooting a few rounds? When?
2. Have you checked the extractor and spring assembly/bolt for damage or chips?
3. Have you examined the spent cases for damage/torn case heads/rim?
4. Have you had any problems chambering a round and ejecting it with out firing it?
5. You need to try a few different types of ammo, get some brass case Winchester or Remington to try to see if the coating on the cheap stuff is causing the problem once it heats up.

I have a X39 AR I built and it has been a joy, mine will shoot good and cheap ammo with out any problems.

[Texas45]

Glad I went with the SRC762 windham for my 762 AR.
Has been 100% flawless in operation.
Guess the redesign for 762 cartridge done to the feed ramp and mags as well as bolt they did was worth waiting for.



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[HankC1]

PSA has good warranty. Just send it back. If you are a member of AR15.com, contact them via forum IM, they have a sub-forum, long wait if you call them.

[turtlehead]

I think we're zeroing in on the problem. The failures increase as the rifle gets hotter. No problems until things warm up.

Extractor spring looks fine as does everything else. Cycling is fine. Bolt holds a round fine. Feeding is fine (as well as can be expected anyway). Afraid to say I did not inspect the cases very carefully. Picked a few up and looked at them and they looked OK. But I really could have been more critical here.

I've heard of problems with lacquered cases but have never had the issue myself. Is that a real thing? I've read arguments back and forth but didn't pay close enough attention.

I don't have any brass ammo at the moment. Just Red Army, Wolf and Tula. Do you think one may be better than the others?

[stagpanther]

I would look for the best quality ammo (and magazines) and see if the problem persists--never made much sense to me to spend a lot of money on a quality weapon and then try to save a few bucks on what you feed it.

[Mobuck]

"Rifle has a 16" PSA barrel with mid-length gas. Chamber looks smooth and clean. Extractor looks fine. Have been using a Spike's ST-T2 buffer (4oz) with chrome silicon spring."

Was there a reason for using the heavy buffer or just fixing non-existent problems(while causing others)? 7.62x39 isn't an extremely high pressure round and often uses a fairly "fast" powder so is less likely to be overgassed(just my opinion). The 16" w/mid-length gas should be OK with a standard buffer.

"The failures increase as the rifle gets hotter. No problems until things warm up."
How "warm" is the barrel getting? I've not had any problems with various types of 7.62x39 ammo but then, I don't "rattle bang" a long string of shots.
It may very well be you have a snug chamber and the el-cheapo ammo is getting gummy from the chamber heat.
Try some decent ammo.

[turtlehead]

The buffer is just what I had on hand when putting the rifle together. They work well in my standard ARs. I will put in the carbine buffer next time shooting.

You're probably onto something with the chamber being a little tight and the ammo being cheap. But I have a whole bunch of it. Will try some brass ammo.

[turtlehead]

And it's after 20 shots hot. Not just blasting away.

[ed308]

Melonite barrel? If so, I'll say again scrub and polish the chamber. Make sure you inspect the lip on the extractor closely which will require removing it. The x39, Grendel and some other cartridges like 270AR and 7mm Valkeryie are rough on extractors. I had a mild load rip the lips off my 270AR extractor, which is the same extractor used in a x39. I was having the same problems as the OP until eventually it wouldn't pull the case when I hit the 200 round mark in that AR.

I've been told this company sells the best x39 extractors. Fixed my problem. But still needed to scrub the chamber.

http://www.shop.ar15hardware.com/pro...?productId=465

[FishinLuke]

When I was doing research piecing my AR47 together, there were multiple threads on forums and articles stating that they recommend a carbine length gas system on an AR47 just for greater pressure for extraction and chambering. There were several reasons behind this but one of the main one is due to the diet of AR47's being steel cased ammo that is generally dirtier than brass cased ammo, as the steel doesn't expand as much to seal off the chamber back from fouling.

I have a carbine length gas, with H2 buffer, AIM 9310 BCG with a Yankee Hill Machine barrel and it's all ran like a top. I have ran Wolf, Tula, and lots of Red Army and have not had one issue (other than a couple of magazine loading issues early one by me) I put some thought and research into the parts I chose.

Either way PSA will make it right if you want to send it back in.

My two brothers and several of my friends have thought about getting an AR47 or have assembled one. And I have always stood by telling them to go with a carbine gas.

I wouldn't doubt that as your gun heats up the fouling from the dirty ammo and lower pressures from the midlength gas might be putting enough friction to cause extraction issues. There are however lots of people out there running midlength gas on AR47's so my way of thinking isn't the only one. I'm sure you'll get it working, and if it was my gun I would measure the buffer spring and compare to others and might cut a half a ring or ring off the spring to get more rapid extraction and see if that helps.

[doofus47]

Increased problems on heating _might_ be lacquer. I only shoot poly-coated steel in my x39 AR and I"ve never had a problem, but when I shot 7.62x54 in my Nagant, it used to lockup the bolt around round 8. I scrubbed the chamber but in the end, the solution was to run a LOT of chain lube through the bolt itself to get out latent cosmoline.
You don't have a cosmoline problem, but you might have a problem with other chemicals turning liquid-sticky when the chamber heats up.

I'm betting on lacquer buildup.

[turtlehead]

Thanks guys. I'm listening. Will let you know how things go after the next range trip.

My other AR47 is a carbine length gas and doesn't have this problem. This one shoots a lot smoother though. Was surprised at such a difference.

Have a great weekend, all!

[FishinLuke]

I want to further state that there seems to be lots of people who have a midlength gas Ar47 that runs fine as well. I'm sure once you find the sweet spot on gas it will be a really nice shooter. I think people like going midlength gas on the Ar47 to allow for the lower pressure on the bolt and longer unlock time on the bolt lugs to take force off them by allowing the pressure to drop in the chamber before unlocking.

I've always been told with all AR's to run the heaviest buffer that will reliably cycle the lowest power and dirtiest ammo. Makes sense to me as it will be easier on bolt heads.

Let us know what you figure out with it.

[ed308]

Mid is the way to go on a x39. And I like mid or rifle on all of my ARs. The mid-length gas system slows cycle speed which helps with accuracy, extraction problems and bolts lasting longer. The x39 bolts take a beating. Right on the edge design wise and what works in the AR15 frame. If I were buying a x39, I'd go with AR15 Performance's x39 and the stronger bolt thats available. But that requires a different barrel extension.

[peggysue]

PSA has good warranty. Just send it back. If you are a member of AR15.com, contact them via forum IM, they have a sub-forum,

[turtlehead]

UPDATE:

Just got back from the range after I made three changes. Switched to a carbine buffer (lighter), a mil spec spring (which was about 3/4" shorter) and cleaned the chamber thoroughly with Eezox (a dry lube/cleaner).

Fired about 50 rounds of the same Red Army ammo with no malfunctions. Good extraction. But the rifle did kick noticeably harder. Went from zero muzzle rise to about 1" rise. No big deal.

And then my scope broke... Before I had a chance to try a different combination of spring and buffer.

It's a Vortex Diamondback HP 4-16x42. The reticle just went cockeyed about 10 degrees. Oh well. Will send it back on Monday and from everything I've read they should make it right.

So we shot some pistols at various distances and had a great time.

All in all, a good day at the range.

[turtlehead]

One more thought. I'd been using BoreTech Eliminator before and think maybe the residue was attracting fouling in the chamber. Just a guess. Maybe it was the spring. Maybe the buffer. Maybe all three.

[tonelar]

worsening as the rifle heats up could be the coating on the steel cases starting to melt and gum up in the chamber