PTR44 Semi-Auto MP44

[timdp]

Mine just started jamming like yours. You might want to take a look at the end of the lever from the trigger group that extends into the receiver and bears on the op rod. Mine appears to be worn off at a 45 degree angle and there seems to be corresponding wear on the op rod. Going to get parts welded back up to spec tomorrow and will take pics.

So we looked at the jamming problem a bit more and found that the problem is with metal deformation on the bottom of the receiver near the trigger group hinge point. Not visible in the photo are metal shavings from where the bolt was wearing on the receiver. Note the location of the bolt in the jammed position. From the top this corresponds to the front face of the bolt being halfway across the top of the mag with the round being halfway stripped from the mag.

In the photo below the side walls were bulged out a small amount at the points where the red arrows are. The bulge was flattened with a pair of angle jaw pliers with not serrated jaws. The two ears marked with green arrows here tapped down a bit with a brass punch. No idea how permanent this repair is but the gun did not jam once during a 30 round mag dump of blanks.

Tim

 

[mrfarb]

By George that's it! Here's a photo of mine in full jam, same as yours nearly. It's odd, they have a round cut right in this area which seems to weaken it or allow the bolt enough drop down to eventually do this. Not sure what a permanent fix would be?

 

[timdp]

Hard to tell but the side walls of yours looks considerably more bulged than mine was. Channel lock pliers with a couple of thin (1/8"+) steel blocks on the sides of the side rails should get it back into shape. Time to get out a straight edge to see how bad yours is bulged.

I suspect permanent fix will involve welding, at least a cross brace across the bottom of the receiver to keep the side walls from spreading/bulging, if not rebuilding the "cut out" edges. Cross brace is assuming there is space in the trigger group to allow it.

Tim

By George that's it! Here's a photo of mine in full jam, same as yours nearly. It's odd, they have a round cut right in this area which seems to weaken it or allow the bolt enough drop down to eventually do this. Not sure what a permanent fix would be?

 

[shortfal]

receiver damage

That slot is there to allow the hammer to pass through. It has to remain open.The place where the carrier is getting caught is normally opened up somewhat wider than the rest of the slot for additional hammer clearance. I've rebuilt original rec. using my rear repair pieces without the widened area. I ended up opening them some when I noticed the hammer clipping the edges.
Looks like some PTR had the slot too wide, allowing the carrier to work its way through.
I'd weld a .065 thick plate over a copper backup in the slot then remachine the slot to minimum width for hammer clearance.
Overkill perhaps?? But a solid fix.
Pete in St. Louis 07/C2

 

[timdp]

Ah yes, the hammer... Glad someone around here knows what they are doing...
Does the slot have to remain open all the way forward? My rifle is packed for a trip this weekend...

Your fix does sound like a good way to go, although Mr Farb will still need to flatten the side wall bulge. The bolt is hitting the forward edge of the opened up area and forcing it open/apart.

Tim

That slot is there to allow the hammer to pass through. It has to remain open.The place where the carrier is getting caught is normally opened up somewhat wider than the rest of the slot for additional hammer clearance. I've rebuilt original rec. using my rear repair pieces without the widened area. I ended up opening them some when I noticed the hammer clipping the edges.
Looks like some PTR had the slot too wide, allowing the carrier to work its way through.
I'd weld a .065 thick plate over a copper backup in the slot then remachine the slot to minimum width for hammer clearance.
Overkill perhaps?? But a solid fix.
Pete in St. Louis 07/C2

 

[gergnotwen]

Anyone have an estimate as to how many rounds were fired before this issue began to show up?

 

[mrfarb]

Can someone post a shot of this area on an MP44? I'd like to compare the manufacturing difference. I'm going to pick up a pair of those pliers today for good measure, but I tapped mine back in place with a brass hammer and brass punch and it seems to have fixed it. It was bulged pretty good.

As to how many rounds, quite a few is all I can say, mostly blank ammo though.

 

[jhv 41]

I have a pdf of the MP44 blueprints if needed.

Too large to post, but I can email.

 

[timdp]

Anyone have an estimate as to how many rounds were fired before this issue began to show up?

1000+, 90% blanks.

tim

 

[GunKraut]

The bottom of my bolt is 0.55" wide but the inside of the receiver measures up to 0.63" which means there's about 80 mils (or 2mm for the metric folks) total sideways play between bolt and receiver. The circular cutout is only about 30 - 40 mils narrower than the bolt and in my rifle the bolt prefers to ride against the right side of the receiver, barely preventing the left side of the bolt flat from catching on the left side of the circular cutout. I'm thinking about reducing the width of the receiver in that area by 20 - 30 mils through careful squeezing. This should still leave enough play for smooth bolt movement while reducing the chance of jamming due to accelerated wear.

 

[gergnotwen]

Can someone post a shot of this area on an MP44? I'd like to compare the manufacturing difference. I'm going to pick up a pair of those pliers today for good measure, but I tapped mine back in place with a brass hammer and brass punch and it seems to have fixed it. It was bulged pretty good.

As to how many rounds, quite a few is all I can say, mostly blank ammo though.

Here you go...

 

[GunKraut]

Here you go...

Wow, big difference on the cutout size and shape. Looks like the PTR is really off in this respect.

 

[gergnotwen]

Look at post #40 and the photos of the bolt carrier. The PTR has no auto sear trip slot in the underside bolt carrier which makes the underside a bit wider than the MP. This potential additional width may be part of the issue as well. I will have to measure my PTR vs. my MP to be sure.

 

[shortfal]

receiver print???

I have a pdf of the MP44 blueprints if needed.

Too large to post, but I can email.

I have the set of prints that a guy on Gunbroker sells as well as what turned out to be an identical set on a disc from a fellow in Germany. Nothing readable for the receiver though .
Do you have a rec. print that is readable? I'd sure like to see it if you do.

Pete in St. Louis

 

[shortfal]

rec. slot

Ah yes, the hammer... Glad someone around here knows what they are doing...
Does the slot have to remain open all the way forward? My rifle is packed for a trip this weekend...

Your fix does sound like a good way to go, although Mr Farb will still need to flatten the side wall bulge. The bolt is hitting the forward edge of the opened up area and forcing it open/apart.

Tim

The slot only has to be open fore and aft enough to let the hammer clear.
Something else to consider is the hammer. The compliance parts (trigger, disconnector, sear, hammer) I have gotten from Recon. are a bit less perfect than MP44 originals. Assuming that's what is in PTR's, the hammer pin hole can be oversize. That could allow the hammer to wobble around side to side and hit the sides of the slot, perhaps adding to the problem of metal being displaced.
Something to look at.
Pete

 

[jhv 41]

I have the set of prints that a guy on Gunbroker sells as well as what turned out to be an identical set on a disc from a fellow in Germany. Nothing readable for the receiver though .
Do you have a rec. print that is readable? I'd sure like to see it if you do.

Pete in St. Louis

Pete,

The receiver group section is close to 15 pages. I've included a couple screen shots here.

The pdf file is much clearer with the ability to enlarge. I sent you a private message if you need additional info.

Regards,

JHV

 

[jack944]

Interesting

I think one thing this thread shows is how complicated it really is to get a weapon to simply function. MP's look rather crude but it seems all the bends and twists of metal have a function. I own 2 and are my favorites German weapons. It is great how this forum is a big help for our community.

 

[d dAY dOG]

It's great that we have a formum again to share our PTR44 experiences. I'm still shooting mine, but not often. Over 1000 rounds and only the occasional mis-feed if I don't push up on certain mags. while shooting it. I do eventually plan on getting a new bolt mated to an original op rod for a spare and also have an original extractor fitted to the gun - but will also need to find or make an extractor pin, which shouldn't be too hard. I have all the spares that Recon offer but for the bolt. Shooting reloads off and on and no issues - using Hornady's reloading data. When the extractor I bought from Recon broke, the op rod/bolt did somewhat lock back into the receiver as some previous posters have described, but mine came out easily enough and there was no damage or warping. Looks like these weren't built like the AK47s we wanted them to be built like. Still, won't be selling mine anytime soon. Besides, if there is almost ANY rifle I see at the local range that I want to shoot, all I have to do is offer 20 rounds through it to the owner and viola ! I get to write off a few more rifles from my list - most of the time.

Good info. people, keep it coming.

 

[shortfal]

ptr44

It's great that we have a formum again to share our PTR44 experiences. I'm still shooting mine, but not often. Over 1000 rounds and only the occasional mis-feed if I don't push up on certain mags. while shooting it. I do eventually plan on getting a new bolt mated to an original op rod for a spare and also have an original extractor fitted to the gun - but will also need to find or make an extractor pin, which shouldn't be too hard. I have all the spares that Recon offer but for the bolt. Shooting reloads off and on and no issues - using Hornady's reloading data. When the extractor I bought from Recon broke, the op rod/bolt did somewhat lock back into the receiver as some previous posters have described, but mine came out easily enough and there was no damage or warping. Looks like these weren't built like the AK47s we wanted them to be built like. Still, won't be selling mine anytime soon. Besides, if there is almost ANY rifle I see at the local range that I want to shoot, all I have to do is offer 20 rounds through it to the owner and viola ! I get to write off a few more rifles from my list - most of the time.

Good info. people, keep it coming.

Get yourself an original bolt with extractor pin and spring along with an original carrier. Do whatever you need to do to the rear of your rec. so that bolt and carrier drop in. (Might not need to do anything). Remove the auto sear trip from the carrier if you find having it there worrysome. Good to go with original MP parts that are NOT known for breaking.
Pete

 

[Model]

Get yourself an original bolt with extractor pin and spring along with an original carrier. Do whatever you need to do to the rear of your rec. so that bolt and carrier drop in. (Might not need to do anything). Remove the auto sear trip from the carrier if you find having it there worrysome. Good to go with original MP parts that are NOT known for breaking.
Pete

Pete, I thought an original Bolt would not fit in a PTR44 receiver? (to large)

Dave.