Help with Pps43c

[Fiorina]

So I bought a brand new Pps43c pistol in 7.62 Tok with the hopes of SBRing it. But so far it's had some problems. At first it had a lot of trouble with short stroking. But after I polished the inside of the receiver and keep the bolt lubed, that's gone away. But now it has an odd problem that I'm not sure of the reason.

At the range today I had zero actual malfunctions. But it has a strange thing it does. Sometimes the recoil is extremely snappy, but then the next shot feels like I was shooting a .22. Virtually no recoil. Then back to hard snappy recoil for a couple shots and so on. This has happened with all 3 ammo types I've used. All new manufacturing. Any ideas?

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[GOG]

I have zero knowledge of your gun. But that won't stop me.

Ammunition is the first thing I'd check. Are you shooting old milsurp? I realize you said you'd tried three types of ammo but it's still worth checking.

Does it have a recoil spring set up? If so it may be worth swapping them out for Wolff springs or some other brand.

Just trying to be helpful, but it's a shot in the dark.

 

[Fiorina]

I appreciate the input. I've only shot new manufactured ammo so it shouldn't be that. As far as recoil spring I'm not sure if it needs to be stiffer or lighter, and I just looked and Wolff doesn't seem to make any Springs for it anyway! Not sure if anybody does.

 

[GOG]

Maybe gunpartscorp/Numrich?

 

[Fiorina]

They only sell complete build kits unfortunately.

I'm just wondering if it's headspace maybe? To have such sharp recoil then virtually none from shot to shot is weird.

 

[Will_White]

I wouldn't describe the pps43 recoil as hard and snappy, about like a .223, have you checked the spent cases? Either your headspace is off or your recoil spring is too weak and it's letting the the bolt move back before pressure drops. Just to verify your pps43 is a closed bolt conversion correct?

 

[Fiorina]

Yes it is a closed bolt conversion. I need to buy a no go gauge I guess. Because my recoil sometimes is far more fierce than .223. Unless it's one of the shots that feels nice and easy. It's like .223 recoil about 20% of the time, the rest are much tougher.

I'm going to try a trick I read about. Sticking a thick washer behind the recoil spring buffer, try to give the spring a little more power.

Oh and I forgot to mention that all my spent casings have had the shoulder blown almost straight. No more bottleneck, they are all pretty close to straight wall cases when I pick them up. And extremely dirty.

 

[SOrez]

I am sure you would have noticed if the barrel was 9MM.

 

[Who The F R U]

So I bought a brand new Pps43c pistol in 7.62 Tok with the hopes of SBRing it. But so far it's had some problems. At first it had a lot of trouble with short stroking. But after I polished the inside of the receiver and keep the bolt lubed, that's gone away. But now it has an odd problem that I'm not sure of the reason.

At the range today I had zero actual malfunctions. But it has a strange thing it does. Sometimes the recoil is extremely snappy, but then the next shot feels like I was shooting a .22. Virtually no recoil. Then back to hard snappy recoil for a couple shots and so on. This has happened with all 3 ammo types I've used. All new manufacturing. Any ideas?

Single base powder is all over the place on consistency . It's MG ammo not Match grade.
+ the hammer conversion might be causing weird influxes if the pin's are loose.

It cant be head space it doesn't lock up they are straight blow back gun's.
Try a new recoil spring.

 

[Fiorina]

I am sure you would have noticed if the barrel was 9MM.

I did a bullet test on the end of the barrel with a 7.62 round and it seemed right.

 

[Fiorina]

A guy from Pioneer (importer) called me back. He wrote down the problems I'm having and is going to have one of their gunsmiths call me back. I will give an update when I hear back

 

[Fiorina]

Ok so I just got off the phone with pioneer again. They are sending me out a new recoil spring to see if that solves my problem

 

[GOG]

Excellent. Hopefully that will be the easy fix.
I've been following this thread, I really enjoy learning this kind of stuff.

I makes me dangerous around hand tools.

 

[Fiorina]

Just as an aside, Atlantic Firearms has been awesome for me. I bought it from them. Ever since I contacted them they have been all over it trying to get me squared away. If pioneers fix doesn't work they said they would make sure I was up and running.

 

[jordanvraptor]

I had one a few years back. It would go full auto on a pretty consistent basis. Especially with Wolf commercial ammo. What was happening is that it would not recoil far enough back to reset the hammer and then it would ride the bolt home. With the Wolf ammo it was enough to fire the round. Other times, the shock of the bolt going into battery would trip the trigger catch or sear holding the hammer back. Same result. I deepened the notch but sometimes it would still runaway. The novelty wore off and cheap surplus ammo ran out so I sold it. My advice would be to do some very hard cycling of the action to see if the hammer is tripped by the jarring. You might be getting detonation of the round before it is fully seated in the barrel? I wish you luck.

 

[Fiorina]

So I think I've got it fixed. I added a leather pad to the back of the recoil plate.