Gunsmithing PTR-91 Issues: Help!!

[mateofeo85]

Good evening ladies and gents. I'm having issues with a friend's PTR-91 action not chambering rounds from the magazine. Any help would be appreciated; pictures with descriptions to follow...

It's a JLD Industries PTR-91 Pistol. Semi-auto, just has a SEF housing on it.


The bolt will lock back when the charging latch is pulled (pretty hard pull to say the least...) It will rack/lock/release without a mag with no problem.


Then I'll insert a mag loaded with surplus 7.62, with the bolt locked back.


As you can see in the following 3 pictures, when I slap the charging latch to chamber a round, the action very sluggishly and/or partially feeds a round from the magazine. The bolt will either barely hit the bottom of the case and stop with the round still in the mag, or pull the round from the magazine, but leave the round partially chambered with the bolt not fully closed.




I've checked the bolt assembly and it seems fine. I've cleaned and lubed the gun per the manual. My only remaining suspicion is that the recoil spring is old and weak. Please advise, HK guru's!!

 

[jetmd]

HK 91, G3 - Stocks, End Caps, Braces - HKPARTS.NET

Replace the spring and the rod guide $18.00 plus shipping and Adam is a top notch Great guy to deal with!

Also while you are working on this weapon check the bolt gap, if you don't know how just search the internet or youtube and you
will find a good tutorial. Super easy if you own a set of feeler gauges.

Good Luck,

Chet

 

[MOAxp]

1. How much movement does the mag have when inserted?
2. If bolt closes completely without the mag I would look at the mag or mag catch

 

[cal50]

The bolt carrier should move freely in the receiver front to rear / full travel.
If its not you are loosing bolt and carrier momentum for chambering.

If you take the end cap off and drop the carrier in the receiver does it move without binding ?

 

[bptactical]

I am not sure if this applies to JLD rifles but check the barrel trunnion carefully for cracks, this is a well documented flaw when US manufacture of the trunnion started. Also check the alignment of the triple frame, it must be true to the barrel and cocking tube. Speaking of cocking tube why does it appear like it is bare metal and has been sanded recently?
Springs are not a bad idea but I would check the magazine catch for wear as well, if the bushing is sloppy it can let the mag sit a smidge lower IIRC.

It's the V51 pistol, I had one for a while and while it is generally useless it is a hoot to shoot. Loud as hell and it belches quite the flaming pumpkin.

 

[mateofeo85]

HK 91, G3 - Stocks, End Caps, Braces - HKPARTS.NET

Replace the spring and the rod guide $18.00 plus shipping and Adam is a top notch Great guy to deal with!

Also while you are working on this weapon check the bolt gap, if you don't know how just search the internet or youtube and you
will find a good tutorial. Super easy if you own a set of feeler gauges.

Good Luck,

Chet

Chet, thanks for the parts link. Seems like a relatively inexpensive attempt for a solution. I had seen some tutorials on bolt gap, but never realized how critical it is.

1. How much movement does the mag have when inserted?
2. If bolt closes completely without the mag I would look at the mag or mag catch

MOAxp, it's pretty snug, not any more movement than an AR mag or similar. I'll take a look closer to see if it is a mag related issue. All I've done so far is make sure that the bolt face will clear the mag when fully inserted. Thanks!

The bolt carrier should move freely in the receiver front to rear / full travel.
If its not you are loosing bolt and carrier momentum for chambering.

If you take the end cap off and drop the carrier in the receiver does it move without binding ?

cal50, I originally caught myself with the rollers not completely recessed when I first started tinkering. But once I disassembled then reassembled the bolt and got the rollers to drop free, there's now zero dragging inside the receiver.

I am not sure if this applies to JLD rifles but check the barrel trunnion carefully for cracks, this is a well documented flaw when US manufacture of the trunnion started. Also check the alignment of the triple frame, it must be true to the barrel and cocking tube. Speaking of cocking tube why does it appear like it is bare metal and has been sanded recently?
Springs are not a bad idea but I would check the magazine catch for wear as well, if the bushing is sloppy it can let the mag sit a smidge lower IIRC.

It's the V51 pistol, I had one for a while and while it is generally useless it is a hoot to shoot. Loud as hell and it belches quite the flaming pumpkin.

bp, I'm going to have to do some research on your suggestions, as my HK knowledge is pretty novice. Great input though, as I never would've gotten it elsewhere.

Not sure why it looks sanded. I'll have to look closer and see exactly what's going on in that picture. And as MOAxp suggested, I'll look more into the possibility of magazine/mag catch issues.

I really want to shoot it; I've got a ton of this surplus that I'm hoping cycles in it once it's running smooth.

Thanks for all the replies. I'll update after implementing suggestions.