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Discussion Starter · #1 ·
Ive shot about 300 rounds through my pmkms, but today I had a problem that cut my day of shooting short. The bolt carrier sticks after I pull it back and then let go. I can forcibly push it forward, but after I shoot a round itll just stick at the back and not load another round. Anyone encounter this problem and know what needs to be fixed?

Ive taken the rifle apart to make sure there was no debris and I even tried a different spring to see if that was the problem but it wasnt.
 

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There are a couple of different thing that will cause this. Here is a paste from the troubleshooting guide I am working on:

"Short stroking" or bolt/carrier assembly sluggish/stops at rear of receiver:

  • *Space between upper rails to narrow
    File or open up a bit

    *Carrier dragging on hammer
    1)Stone area of hammer that contacts the carrier
    2)Try a different hammer

    *Rear trunion place too far rearward, carrier will usually come out of receiver too
    1)Remove weld up hole, drill in correct spot rerivet trunion
    2)Add a buffer to take up the space

    *Hammer or trigger pin walking out
    Put back in proper position reinstall shepherd crook correctly

    *Insufficient gas flow
    1)Check for carbon build up in gas chamber/gas port
    2)Check for barrel being drilled for gas port
    3)Check for burr/dent in gas chamber
    4)Check for severly worn gas piston

From what you discribe, I would say either the rails are tight or the rear trunion is too far back. To check the later, remove your top cover. Reinstall the recoil spring assembly. Rack the carrier as far rearward as it will go. With it all the way back, try to lift it out of the receiver. You shouldn't be able to. If you can, the buffer is your easiest fix. If you can't, see if it will stay there. If so, you probably have tight rails. Check these two things and let us know what you get. If more help is needed, feel free to ask.
 

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Discussion Starter · #4 ·
thanks for the reply Kalashnikox, Ive been fiddling with it and it seems that its stopping on the hammer. Right now it functions fine if I let the bolt fly forward normally, but if I manually hold onto it and let it go forward it seems to stop at the hammer. I guess when the rifle heats up it just gets alot worse and wont even go forward on its own. Heres a couple pics of where its stopping.



 

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G2? Been hearing a few things like this recently about them. Ever thought of an RSA? They are a bit more expensive, but well worth the extra $.
 

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Discussion Starter · #6 ·
I just got done taking the fcg apart and I put the rifle back together with the original hammer that came with the pmkms kit. Unfortunately its still messed up. I think Im just gonna grind the hammer down and hope for the best!
 

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Discussion Starter · #7 ·
Ive ground the hammer down a bit and its definetly helping, Ive had enough of it for today. Ill probably grind it down some more in the next day or so and it should be smooth as silk. Ill take a pic of it when im done.
 

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Don't grind the hammer down. Most AK carriers hang up on the hammer if you lower them back. My Polytech does that too- I can actually reload by pulling the bolt/carrier back slowly, removing and inserting a new magazine, and then slapping the rifle to let the bolt and carrier slide forward and chamber a new round.

With the new hammer, yank the charging handle back. Do not be soft or gentle. If it slams foreward, good. Go shooting next time with that new hammer and see if it works. It will also help to use a strong polish, like M.A.A.S., on the bottom of the bolt and on the hammer, then finish with a light lubricating oil.
 

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Discussion Starter · #9 ·
Heres a pic of where I ground the hammer down. It made a big difference, it still hangs if I manually hold the carrier and go forward but all it takes is a little flick of my finger and it flys forward. Before I actually had to use some force to get it to go forward. Hopefully when I go shooting nexttime and the rifle begins to heat up it wont start to stick again.

 

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Discussion Starter · #11 ·
5thShock said:
Stay clear of the hammer face, the area that strikes the firing pin. Let everybody know how it works out. Good Luck.
Ya I tried to stay away from that, barely got it a couple times, but Ive checked it and it looks like its still hitting just fine. Ill be able to go shootin next friday and Ill post here to let you all know how it went. Thanks for all the help!
 

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Discussion Starter · #12 ·
Shot about 200 rounds today. Its nice and smooth with no problems at all if I just shoot normal 1 round at a time. When I try to bumpfire though every 7th or 8th round will misfire and I have to eject and load the next round. Sometimes the bullet would actually fire, but it wouldnt eject the casing and I would have to do it myself and load the next round.

Only thing I can think of causing this problem is the ammo, I was using the 154 gr. wolf soft points. Anyone got any other ideas? Next time I go out Ill try the wolf fmjs.
 

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Were you using the 154 grain when the problem first appeared? If not, if you just now started using the 154 it could be a separate issue.
 

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Discussion Starter · #14 ·
5thShock said:
Were you using the 154 grain when the problem first appeared? If not, if you just now started using the 154 it could be a separate issue.
yep, the wolf 154 sp is the only ammo Ive sent through the rifle so far.
 

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ohsonofa said:
Shot about 200 rounds today. Its nice and smooth with no problems at all if I just shoot normal 1 round at a time. When I try to bumpfire though every 7th or 8th round will misfire and I have to eject and load the next round. Sometimes the bullet would actually fire, but it wouldnt eject the casing and I would have to do it myself and load the next round.

Only thing I can think of causing this problem is the ammo, I was using the 154 gr. wolf soft points. Anyone got any other ideas? Next time I go out Ill try the wolf fmjs.
Since there is no auto sear trip, you are pulling the trigger before the bolt is in battery and the hammer is riding it forward. The hard primers in the Wolf will not slamfire so you get a misfire. You need to loosen your grip to lower the rate of bumpfire.

As for the failure to eject, I have no idea.
 

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Discussion Starter · #16 ·
Since my last post in this thread Ive polished the fcg and I added a blackjack buffer (the black one). Went and tested the rifle today and its perfect. Was able to bumpfire with no problem at all. Now I dont know if me polishing the fcg did it or the blackjack buffer, but Im pretty sure the buffer did the trick. Nexttime Ill try bumping without the buffer just to see. Oh also, this time I was shooting the wolf 123 gr FMJ and not the 154 gr sp, so that might have been a factor as well.
 

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Be mindful of your grinding area. Most metal is only 'surfaced hardened' and if you grind too much, you will grind off the hardened surface and expose the softer inner portion. If you see wear suddenly developing, you can harden it again with a case-hardening compond that I believe can be obtained from Brownell's.

Happy Shooting
cya
 
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