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Posted: 12/16/2014 1:53:15 AM EDT
So my PPSH41 ejects all of it's rounds and goes bang every time, but the rate of fire of the gun is all over the place, and this is with good new S&B ammo.  Could this be drum and mag related or something else?

Here is what I notice.

Sometimes it throws the brass 5+ feet in the air.  When it does this, the rate of fire is perfect and fast.  Then it'll thrown some rounds just inches into the air and the rate of fire slows down.  It's as if some random bullets have less power, but I know that's not the case with new S&B ammo.  Could it be that the bolt is dragging on the round in the drum, or dragging while pulling the empty case out of the chamber?  Is this a problem that pops up with drums more often?  It did it still, but not as bad with my stick mag.

Same thing can happen in semi auto.  I'll shoot, and sometimes it throws the brass nice and high and it shoots just one round.  Then every now and then a round only shoots a case inches in the air, and 2 rounds will fire with just one trigger pull.  As if the bolt didn't go all the way back to get caught.

I'm really not sure what the hell is wrong here.  I'm glad the gun runs, but I cant figure it out.  Spring, drum, brass vs steel case, etc???  I've only shot it with S&B brass cased ammo, but have steel cased RedArmy and PRVI brass cased ammo coming in on Thursday to try out.

I've also been asking this questions on machinegunboards, and somewhere there mentioned their ejector causing a similar issue, so I checked mine.  Here is what I found.........

I just now took the spring and rod out of the gun and held the trigger down so I could move the bolt forward and backward freely.  When it is all the way back it's sitting level, but as I push it forward slowly it does actually hit the top of the ejector and raise maybe 1/2 - 1mm.  Is this normal?  I've never seen a gun do this before.  Should I take a dremel to the top of the ejector and shave off 1/2mm so it glides over it freely or is this normal?

Thanks for all help and advice
Link Posted: 12/16/2014 9:51:51 AM EDT
[#1]
Never had this exact problem with my Ppsh. Yes, my bolt will ride up just a smidge when going over the  ejector. But some things to check.

 1) is your drum wound correctly? I mean with the drum empty, Wind it a click so you can remove the follower. Then, holding the guts, push the release and let it unwind. Yes, the bitch will jump and try to slice your finger tips, don't let it. Rewind the drum the correct number of times. Mine are wound about 2 1/2 times. Put the follower back in and tighten it's screw. See www.Ppsh41.com for better instructions. The drum is 90% of a Ppsh's problems running.
 2) Look at where the bolt handle would hit the stop on the right side of the receiver. Is it freshly damaged? If so, the rounds are too hot or your buffer and or spring is junk. The buffer spring is pretty weak to begin with. That is why you have that you have a big fat chunk of leather back there to cushion the bolt.
 3) Check the receiver for flatness. Pop out the hinge pin and set the upper receiver on a flat surface from the chamber back. Is it bowed up in the middle? Mine did that after shooting some overly hot ammo. I basically took a hammer and beat it down to straight.
Link Posted: 12/19/2014 12:00:24 AM EDT
[#2]
UPDATE for those that may encounter a similar problem.

I went to Military Gun Supply yesterday and picked up a new Polish parts kit for $170. They just opened that day after the shooting last Saturday.  So sad.  I hope they catch the SOB.

I put in the new recoil spring, and it did allow me to tune the drums 2 full turns tighter.  Smoothed things a lot, but with S&B it was still a little wonky.  I then tried a stick mag, nice and smoother as well.

Then I started trying two different brands of ammo.  I've been shooting S&B this whole time assuming it was the best.  Well I can report back that with the PPSH-41, it is not.

The PRVI ammo, ran perfectly smooth, just slightly slower.  Then the biggest surprise was that the cheapest ammo, Red Army Standard, was also perfectly smooth and had a nice fast rate of fire with flames shooting out the front.  It was bad ass.  I went back and forth with all ammo brand, drums, and sticks, and I can report back with 100% certainty, that my gun runs freaking amazing with the cheapest ammo.  Steel cased Red Army Standard 7.62x25.  VERY interesting to say the least. It runs the worst with the priciest ammo S&B.  It runs perfect, but slow with PRVI.  

Weird.  Time to sell all my S&B and buy a pallet of Red Army Standard for 2/3 the price.
Link Posted: 1/2/2015 12:10:59 PM EDT
[#3]
My experience although limited with a PPSH was that ammo affect ROF a lot , I saw changes from brand to brand and with surplus as well.  , more than any other machine gun I have shot .  At the end of the day it ran it all and I was happy
Link Posted: 1/2/2015 12:14:04 PM EDT
[#4]
My m11/9 with max kit has a variable rof with target ammo. Bolt doesn't consistently impact buffer.
With good ammo it hits the buffer every round and is very consistent.
Link Posted: 1/2/2015 12:15:08 PM EDT
[#5]
Stick mags only for me so your tuning the drum for less drag on the bolt would be good.
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