Issue with AR15 in 7.62x39

djmagnum

djmagnum

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Hi everybody

I am posting today because I am looking for some help from the community. I bought a PSA 7.62x39 10.5 complete upper, with BCG from IRG and I am having some issues with it: it gives me FTE (Fail To Eject) issues in a very inconsistent manner. It can be once every 5 rounds, can be OK for 15-20 rounds and then fail 2-3 rounds in a row.

The symptoms are that the spent shell casing exits the chamber completely (no Fail To Extract), but not the upper receiver and does not exit by the ejection port. It does not ends in a stovepipe: it just get rammed back with a new round from the mag and jams the weapon because a double feed.

I have tried running a heavier buffer (H2) with same result. I also replaced the original (PSA) extractor spring with a much stiffer Wolff one: same result. Bolt and rifle was completely cleaned and I run it well oiled with CLP.

I did some tests today : I tried several different mags (XCR-L pistol from Questar) with several different loadout (1-2-3.. rounds) : no difference. I also tried brass American Eagle ammo versus Barnaul steel case : no change.

Last test I did was to load a round, then drop the mag and fire: sometimes the empty shell case would get re-loaded in the chamber!! If I tried the same thing, but kept the empty mag inserted (last round in chamber type of thing), the BCG would remain in the back and the empty case would just sit in the upper receiver, over the mag ...

I am suspecting a problem from the extractor and/or the ejector but any input would be appreciated.
 
It MAY be overgassed to a point that the bolt carrier group is moving and unlocking the bolt before the cartridge case has shrunk enough in the chamber. Try an H3 buffer, perform a very thorough chamber cleaning, different ammo (steel, brass case and different bullet weights).

Also a contradiction to my previous comment it can be also under-gassed by having the gas block severely out of alignment. Low profile block that was banged or having it move from a drop? Gas port size, gas key loose, leaking gas tube or gas block?
 
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Sqr said:
It MAY be overgassed to a point that the bolt carrier group is moving and unlocking the bolt before the cartridge case has shrunk enough in the chamber. Try an H3 buffer, perform a very thorough chamber cleaning, different ammo (steel, brass case and different bullet weights).

Also a contradiction to my previous comment it can be also under-gassed by having the gas block severely out of alignment. Low profile block that was banged or having it move from a drop?
Click to expand...

sounds like not enough gas to complete the cycle, before the buffer spring tension overcomes the momentum or the BCG.
 
Sqr and hbean: the OP specifically mentions it's not a failure to extract as the case fully exits the chamber but does not exit the gun. He also points out that if he chambers one round without the mag, it will reload the spent case into the chamber. If he puts the mag in with one round in the chamber, it will lock back on the empty mag and the round is sitting on top of the empty mag.

It is not a gas issue. It will cycle, pick up a fresh round, and lock back. Also no stovepipes.

The extractor is doing it's job enough to clear the case from the chamber, however it's still possible the spring is weak but unlikely since you replaced it.

Its also very likely the ejector spring is weak or the ejector is sticking.

OP- check the ejector is stiff but moves without sticking. Also try pulling the extractor away from the face. It should be reasonably stiff to move by hand. If it's really easy to move by hand, replace the spring and/or add a donut if it doesn't have one. But i doubt it's the extractor since you replaced it with a wolf one already
 
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*MALICE* said:
Sqr and hbean: the OP specifically mentions it's not a failure to extract as the case fully exits the chamber but does not exit the gun. He also points out that if he chambers one round without the mag, it will reload the spent case into the chamber. If he puts the mag in with one round in the chamber, it will lock back on the empty mag and the round is sitting on top of the empty mag.

It is not a gas issue. It will cycle, pick up a fresh round, and lock back. Also no stovepipes.

The extractor is doing it's job enough to clear the case from the chamber, however it's still possible the spring is weak but unlikely since you replaced it.

Its also very likely the ejector spring is weak or the ejector is sticking.

OP- check the ejector is stiff but moves without sticking. Also try pulling the extractor away from the face. It should be reasonably stiff to move by hand. If it's really easy to move by hand, replace the spring and/or add a donut if it doesn't have one. But i doubt it's the extractor since you replaced it with a wolf one already
Click to expand...

If it's overgassed the bolt carrier traverses rearward as the extractor skips over the rim before the case swelling subsides enough. However some cases can partially extract.
 
I had issues with a piston in my SKS that ended up causing the same issue. Results of a piston that slid freely through the gas tube made it eject very weakly, then double feeding because it would just catch the next round. Swapping it out with my other sks' piston fixed up the issue as it was a better fit in the tube.

My guess is you're either over/under gassed
 
Except that (he says) the cases are fully extracting. And the fact he has already put a wolf extractor spring in makes it unlikely the extractor is slipping off the case (although not impossible). Also, steel cases dont expand as much as brass cases.

It's unlikely that the gun is so overgassed that even adding the H2 buffer failed to have any impact. And it has enough gas to lock back on empty.

Op- what direction does it eject when it does eject

You can swap your ejector and selector springs. They are the same.
 
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Here is well written article on trouble shooting an AR https://www.americanrifleman.org/articles/2014/8/14/the-ar-15-for-home-defense-reliability/


A 7.62X39 round with a typical chamber pressure around 45000-51000 PSI running in an rifle designed to run the 5.56 round with a typical chamber pressure of 55000 to 62000 PSI. The Mil spec gas port size for 5.56 chambered 16" carbine length barrel is 0.0625" and the gas port size for a barrel chambered in 7.62X39 with everything else being the same is between 0.078" to 0.0938".

I pretty sure the OP is shooting military grade ammo made in China or some Eastern European country, they well know for producing under power rounds, so the combination of a low power round and a restrictive gas port is a more likely culprit here, since what the OP has described here is dead ringer for short stroking and I have had a similar problem with my Dlask 7.62x39 upper until I open up my gas port to 0.12 or 1/8".
 
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Ok. For the sake of argument let's assume this is a gas issue.

The proper solution to being undergassed, assuming his gas block isn't misadjusted, is to open the gas port. Sure, one could try running a lighter buffer or removing weights from the existing one, but that may or may not solve the problem. And if its not really undergassed, you risk wrecking the barrel. This task may also be beyond the scope of the op's skills.

The solution for it being overgassed is to buy an adjustable gas block and tune it down but those tend to be expensive for good ones. The op could try a heavier buffer (but he already tried H2 and it didn't help so it's unlikely H3 will). He could also shift the gas block forward to partially obstruct the gas port.

Maybe im wrong with the ejector, but he already has a spare built into the gun (selector and ejector spring are the same) so it will cost him nothing to try that first.
 
*MALICE* said:
Sqr and hbean: the OP specifically mentions it's not a failure to extract as the case fully exits the chamber but does not exit the gun. He also points out that if he chambers one round without the mag, it will reload the spent case into the chamber. If he puts the mag in with one round in the chamber, it will lock back on the empty mag and the round is sitting on top of the empty mag.

It is not a gas issue. It will cycle, pick up a fresh round, and lock back. Also no stovepipes.

The extractor is doing it's job enough to clear the case from the chamber, however it's still possible the spring is weak but unlikely since you replaced it.

Its also very likely the ejector spring is weak or the ejector is sticking.

OP- check the ejector is stiff but moves without sticking. Also try pulling the extractor away from the face. It should be reasonably stiff to move by hand. If it's really easy to move by hand, replace the spring and/or add a donut if it doesn't have one. But i doubt it's the extractor since you replaced it with a wolf one already
Click to expand...

As you have pointed out and it Doesn't cost anything checking these. However if one is seized it usually hinders going into battery and even with an ejector being weak they can continue to eject from the shear violence of a carbine cycling action.
 
Sqr said:
It MAY be overgassed to a point that the bolt carrier group is moving and unlocking the bolt before the cartridge case has shrunk enough in the chamber. Try an H3 buffer, perform a very thorough chamber cleaning, different ammo (steel, brass case and different bullet weights).

Also a contradiction to my previous comment it can be also under-gassed by having the gas block severely out of alignment. Low profile block that was banged or having it move from a drop? Gas port size, gas key loose, leaking gas tube or gas block?
Click to expand...

Hi there

I tried a standard, H1, H2 and H3 buffer with no difference: the issue remains te same. The whole upper is factory built by PSA with a standard-looking AR gas block/front sight; I do not know the size of the gas port though. Chamber is clean and diffrent ammo will not change anything ...even with brass, American Eagle and Remington. I did not fire as much brass ammo (~40) as I did steel (Barnaul and Czech surplus) but the brass one even had a higher rate of failure.
 
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Mine was the Ar47 by PSA if that's the one you have that irunguns brought in last year or before. Let us know if you find a fix! I haven't tried messing with mine yet but had bought an h2 and h3 to try. I have the same issue as you do.
 
i just bought a 10.5 inch psa pistol upper the guy who sold it said he fired 280 rounds of non corrosive in it with not one problem hope i did not get a lemon if its that bad i would be sending it back to psa for warrenty
 
Have you tried to cycle the rifle by the charging Handle and a round in the chamber to observe if it pulls the cartridge and ejects it out the port? Borrow a bolt carrier group or loan yours to see if the symptoms persist in another AR.
 
This isn't a gas issue.
It's the extractor and ejector springs on the bolt - they are weak. The PSA guns and uppers were über cheap themselves, and this is where they saved the coin.
I put around a thousand rounds down range on mine in the first week I had it and the springs came out of it limp. While the carpenter steel bolt is ok, there is much better available.
Change out to an LMT enhanced and don't look back.
I've a spare PSA bolt for anyone that needs one for cheap...

 
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+1 on the LMT bolt. Once you get the thing running you'll probably start to break extractors. My custom built AR upper came with a DPMS bolt and it would break an extractor very few hundred rounds. I replaced it with an MGI Enhanced bolt, but didn't shoot it for that long before the LMT bolts became available again so I didn't get to test its longevity. I bought a spare extractor with the LMT bolt since it's proprietary and I didn't want to be without in case it did break. It hasn't. LMT said that they've never seen one of their extractors break, but again since it's proprietary I chose to get a spare. It has been running like a champ since I got it. I can't say enough good things about it.
 
spooky.
I logged in to ask the community for suggestions on a new 7.62x39 bcg as I have the exact same issues with the exact same rifle as the OP.

PSA with 10.5" barrel, purchased off EE with no suggestion from the user that there was a known issue.

I already tried the H3 Buffer from Spikes Tactical and it seemed to work well for a bit but now, after a few dozen rounds it has stopped ejecting and the spent round actually remains stuck in the chamber on occasion as well. I had to use a cleaning rod to eject the last time I fired it. It will not eject when I cycle manually, using the Charging handle.

It was working when I used a DPMS bcg I have in my Spike's lower.

I am going to look into an LMT next.


thanks,
 
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