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View Full Version : PTR91 GI will only cycle steel case ammo


TacoJockey
07-05-2012, 8:25 AM
I bought a PTR91 GI a couple months back and ran about 150 rounds of brass case ammo (factory american eagle 150 gr, reloads of the same cases, reloads of once fired LC) through it before I started having problems. No it will cycle the first two or three rounds, but after that it becomes a single shot and refuses to cycle at all. Everything else on the gun seems ok, chamber flutes are completely clean, chamber is dry, light lubrication (rem oil) on the rollers and carrier. I took it out to the range yesterday with the same brass case ammo I had been using but also brought some Tula just to see if it made a difference. The brass ammo still failed to cycle, but the Tula cycles perfectly and flings the cases better than 20 feet forward. When I check the cases of the spent brass ammo, it looks like the brass is flowing into the chamber flutes, I'm guessing this is why they wont cycle. My question is, is there a way to aid the brass cases in extracting such as applying a LIGHT lubrication to them before firing (I'm thing of some type of dry lube)? I'm thinking the steel cases work becuase they are made of a harder material and have the polycoating.

jsipe007
07-05-2012, 10:00 AM
Thats odd... I have never heard of that problem. Does the extractor rip the rim off the brass cases? Or does it completely fail to move the case at all? Are you still using the factory AE and reloads?My coworker has a PTR91 and his cycles brass cased ammo perfectly. He doesn't lube the cases. I want to say it flung the brass at least 20 feet forward, maybe closer to 30. Maybe try contacting the company and see if anyone has any advice?

Holescreek
07-05-2012, 10:10 AM
Post a photo of a spent brass case. This condition is typical of chambers where the shoulder flutes are too deep and the brass catches in them.

jsipe007
07-05-2012, 10:11 AM
The only other thing I can think of is that maybe the ejector got bent? but since it shoots steel case ammo fine, thats an unlikely culprit. Still, Id try removing the ejector group. Lay it on a flat surface and see if theres any bends to it. It should lay flat. if it doesnt lay flat, try bending it back slowly and see if that helps.

jsipe007
07-05-2012, 10:15 AM
The flutes could easily be the problem, especially with the cases as described. Im surprised though, since you stated it fired 150 brass cased rounds not too long ago. the early PTR's commonly had chamber flute issues preventing them from cycling mil-surp ammo, but the PTR GIs had this issue resolved for the most part.

Eddy's Shooting Sports
07-05-2012, 10:24 AM
Does the extractor rip the rim off the brass cases? Or does it completely fail to move the case at all?

???

The PTR is a retarded blowback system. The extractor has nothing to do with case coming out of the chamber. Unless you are unloading it with the charging handle....

TacoJockey
07-05-2012, 10:34 AM
Using brass cases the bolt/carrier barely moves rearward, if at all. I'll post some pictures of the cases tonight, the flute marks on the neck/shoulder of the brass are very evident with the brass obviously flowing into flutes at firing, the body of the cases genelly only shows the black carbon markings from the flutes but is not deformed much if at all. I checked the ejector when I cleaned the gun last night, it appeared straight and moved freely in the bolt slot, but doesn't have excessive play. I didn't save any of the steel cases to take pictures, but when I looked at them all they had was black fouling from the flutes, no deformation of the case. I have a port buffer on the gun, I'm sure the empty steel would fly farther if it wasn't there.

FeuerFrei
07-05-2012, 10:37 AM
Reloads failed to cycle?
Full length sizing die and case trimmer used to prep reload cases also?
Don't lube ammo.
Tula works because it is new and lacks the PTR love bites on the case.

TacoJockey
07-05-2012, 10:54 AM
Reloads failed to cycle?
Full length sizing die and case trimmer used to prep reload cases also?
Don't lube ammo.
Tula works because it is new and lacks the PTR love bites on the case.

All the reloads were FL resized, verified with a Wilson gauge, and trimmed to the 'trim-to' length. All the flute marks are removed during resizing. Out of the 150 or so brass rounds that worked well, half were factory American Eagle, the other half reloads. I know the issue with lubing ammo is increased pressure on the bolt and the case possibly not sealing the chamber, however with this weapon pressure from the case on the bolt is exactly what makes the gun cycle, and the flutes are present in the chamber so that the chamber isn't sealed.

TacoJockey
07-05-2012, 10:58 AM
Oh, and also, the bolt gap is in the acceptable range at .012 and the trunnion isn't cracked.

jsipe007
07-05-2012, 11:14 AM
@Eddy how does the PTR eject casings then? I was under the impression an extractor grabs the rim of the case and then blowback after firing pulls the case from the barrel. I don't personally own a PTR, but Ive shot a few. I've also seen pics where a PTR ripped the head of the case off from the violent extraction.

Holescreek
07-05-2012, 11:23 AM
The DRLB actions use the chamber flutes to channel propellant gasses backwards through the flutes to float/push th e cartridge out of the chaber. The extractor merely holds the cartridge against the bolt face long enough for the ejector to kick it out.

Steel cases do not expand into the flutes like brass and is doesn't grab into the channels. When diagnosing ejection issues we always end up with the question, does it do it with steel cases? The other question is are the brass cases commercial .308 since NATO cases are thicker and tend to expand less. Personally, if it's under warranty I'd send it back and let them make it right.

Richard Erichsen
07-05-2012, 11:27 AM
...I took it out to the range yesterday with the same brass case ammo I had been using but also brought some Tula just to see if it made a difference. The brass ammo still failed to cycle, but the Tula cycles perfectly and flings the cases better than 20 feet forward. ...I'm thinking the steel cases work becuase they are made of a harder material and have the polycoating.

Steel cased ammo works in these rifles consistently, soft, thinner brass cased commercial .308 can be hit and miss. What serial and manufacture date did you have on your rifle? Earlier rifles had chronic problems with flutes due to the early Wilson contract barrels having only 10 narrow, shallow flutes, then later 11 flute barrels that were still deficient on flute depth. More recently they are 11 or 12 flute, made by Thompson Center and have the correct depth and width.

NATO brass is a bit thicker in the wall and web and may be somewhat harder as well, making it less prone to flow into the flutes. Steel cased is of course harder still and so virtually never suffers this problem. If you try some 7.62 NATO surplus, I'm betting your problem goes away. As mentioned, it could come down to the production timeframe of your rifle and source of the barrel. The latest incarnation are purportedly tolerant of just about any ammo, brass cased .308 commercial types included.

R

jsipe007
07-05-2012, 11:27 AM
Ah ok. Thanks for the clarification. The extractor on a PTR is purely for charging and doesnt actually function as an extractor when firing the rifle.

@Eddy, I see what you mean now. I was under the misconception the extractor grabbed the lip of the case then functioned in conjunction with the blowback to eject the spent casing.

This being the case, I would get a HK flute brush and clean the flutes to see if that helps, or send it back to PTR.

RP1911
07-05-2012, 11:27 AM
Shot in the dark, not familiar with the PTR91 much so not sure if this applies, headspace correct?

jsipe007
07-05-2012, 11:30 AM
OP, from what I have heard on the internet, I would be wary sending your rifle back to PTR though. On another forum (not sure how reputable though) a guy said PTR told him they would bill him for the time and money to service the rifle if it shot ok with their ammo. I would ask, but if they say the same thing, I'd probably just buy a bunch of steel case military surplus ammo.

FeuerFrei
07-05-2012, 11:31 AM
Sounds like your case prep is sound.
...so some reloads are causing issue and factory American eagle or wolf cycles fine?
First few rounds cycle fine and then it gags?
I used to reload for a KH91 back in the 80"s and only had to worry about case heads getting ripped off after too many re-uses of the brass.
Being a delayed blowback system it should run just about any load that it's designed for.
I can only guess a magazine issue or a ammo pressure issue at this point.
My current PTR eats everything too and I only run wolf or german surplus in it.
Bad ammo was the only thing that would make it not cycle.
Let us know what you find. Good luck.

Richard Erichsen
07-05-2012, 11:34 AM
@Eddy how does the PTR eject casings then? I was under the impression an extractor grabs the rim of the case and then blowback after firing pulls the case from the barrel. I don't personally own a PTR, but Ive shot a few. I've also seen pics where a PTR ripped the head of the case off from the violent extraction.

On these rifles, the case is pushed out under the pressure of firing - there is no gas piston or gas tube impinging to thrust the bolt carrier back in order to pull it out in the conventional manner.

Case head separations are caused by using ammo too short for the chamber (a true 7.62 NATO chamber is longer than a .308 Winchester chamber) and very dirty chambers that don't vent gas from the case mouth back along the walls of the case to unstick them and float/thrust them out while chamber pressure is still quite high. The geometry of the rollers, locking piece angle and trunnion ramp angle is what retards the timing of the blow back operation in what borders on black magic even when you have a grasp of the basics.

R

Richard Erichsen
07-05-2012, 11:37 AM
Sounds like your case prep is sound.
...so some reloads are causing issue and factory American eagle or wolf cycles fine?
First few rounds cycle fine and then it gags?
I used to reload for a KH91 back in the 80"s and only had to worry about case heads getting ripped off after too many re-uses of the brass.
Being a delayed blowback system it should run just about any load that it's designed for.
I can only guess a magazine issue or a ammo pressure issue at this point.
My current PTR eats everything too and I only run wolf or german surplus in it.
Bad ammo was the only thing that would make it not cycle.
Let us know what you find. Good luck.

Early prototype CETME rifles which gave birth to the G3 and the proliferation of DRB actions in general used lubricated cases in smooth chambered barrels. However, this was obviously not very successful since they carried fluted chambers not long afterward and models from the Model A onward were always fluted. There are as many as 16 flutes in some recent HK weapons.

Lubing the cases is only dealing with the symptoms. The root cause is the chamber flutes. If the chamber is indeed clean, then the time period for fussy barrels is somewhere in the early PTR or late JLD days. The manufacturer may honor a warranty claim and replace, it's worth a try.

R

Richard Erichsen
07-05-2012, 11:39 AM
The only other thing I can think of is that maybe the ejector got bent? but since it shoots steel case ammo fine, thats an unlikely culprit. Still, Id try removing the ejector group. Lay it on a flat surface and see if theres any bends to it. It should lay flat. if it doesnt lay flat, try bending it back slowly and see if that helps.

The ejector lever won't do anything unless the carrier slides back with an intact case still clamped in the extractor in the head. Failure to eject is a separate and distinct failure from that of failure to extract.

R

Richard Erichsen
07-05-2012, 11:44 AM
Shot in the dark, not familiar with the PTR91 much so not sure if this applies, headspace correct?

Conventional headspace doesn't exist on these rifles. We have "bolt gap." Unlike headspace, we start off with a range in bolt gap from .004-.020" and it only shrinks until the rifle malfunctions because it doesn't have enough gap (effecting timing) to cycle properly. In rifles with rotating bolts we have headspace that only ever gets larger. They don't correlate to each other at all, DRB is it's own strange animal.

R

RP1911
07-05-2012, 11:46 AM
Conventional headspace doesn't exist on these rifles. We have "bolt gap." Unlike headspace, we start off with a range in bolt gap from .004-.020" and it only shrinks until the rifle malfunctions because it doesn't have enough gap (effecting timing) to cycle properly. In rifles with rotating bolts we have headspace that only ever gets larger. They don't correlate to each other at all, DRB is it's own strange animal.

R

Thanks for the education. :) learned something new.

TacoJockey
07-05-2012, 11:50 AM
Sounds like your case prep is sound.
...so some reloads are causing issue and factory American eagle or wolf cycles fine?
First few rounds cycle fine and then it gags?
I used to reload for a KH91 back in the 80"s and only had to worry about case heads getting ripped off after too many re-uses of the brass.
Being a delayed blowback system it should run just about any load that it's designed for.
I can only guess a magazine issue or a ammo pressure issue at this point.
My current PTR eats everything too and I only run wolf or german surplus in it.
Bad ammo was the only thing that would make it not cycle.
Let us know what you find. Good luck.

Both the reloads and factory AE worked fine for a time, now its only the steel case that works. I was thinking magazine as well but I changed mags with the same result, also the steel and brass case were shot using the same mags. I haven't used any foreign nation surplus, however I did use some LC cases, same result. This GI version should have the correct number of flutes, cut correctly.

I only bought this a couple months ago so I'm well within the warranty period, PTR website says the warranty card has to be sent in within 30 days, hadn't done that yet so hopefully they wouldn't deny just based on that. I'll call them and see how it goes...

TacoJockey
07-05-2012, 11:53 AM
Serial is GI9XX, so outside the range for the trunnion issue. I did check it though, trunnion not cracked.

jsipe007
07-05-2012, 12:09 PM
Well Im glad to see youve got an arsenal of help now for your problem! The PTR91 has always been a favorite of mine (I just like the style) but like any rifle its clearly not perfect. Thanks for the education, and hope you get that rifle working flawlessly!

TacoJockey
07-05-2012, 12:38 PM
Just got off the phone with PTR. They agreed it was strange for it to just stop working with brass ammo after 150 rounds and to try a different commercial ammo just in case, otherwise they will take it back in and check it out. I'll go get a box of remington UMC, doubt it will work but at least I know they're willing to take a look at it.

Richard Erichsen
07-05-2012, 5:04 PM
Serial is GI9XX, so outside the range for the trunnion issue. I did check it though, trunnion not cracked.

We still need a pic or two of your brass cases to determine from the marks what might be going on.

R

Richard Erichsen
07-05-2012, 5:05 PM
Just got off the phone with PTR. They agreed it was strange for it to just stop working with brass ammo after 150 rounds and to try a different commercial ammo just in case, otherwise they will take it back in and check it out. I'll go get a box of remington UMC, doubt it will work but at least I know they're willing to take a look at it.

Don't forget to photograph the spent cases!

R

TacoJockey
07-05-2012, 8:53 PM
Ok so here's an example of the brass casings. The fluting is pretty obvious on the necks and shoulders, but trails off farther down the body of the casing. If I end up sending it back to PTR I'll print them out and include them with the gun.

http://i1051.photobucket.com/albums/s436/mattbuescher/20120705_213345.jpg

http://i1051.photobucket.com/albums/s436/mattbuescher/20120705_213411.jpg

http://i1051.photobucket.com/albums/s436/mattbuescher/20120705_213534.jpg

Holescreek
07-06-2012, 6:45 AM
With regards to your brass, notice the transition in flute width at the bottom of the shoulder transition to the sides. The flute width at the neck is so wide that the brass has flowed into it blocking off the gas flow, what does make it past is meeting the narrowed passages at the side transition.

Essentially this is what I imagine your chamber looks like. This was one of the failed early PTR (Thompson?) barrels:
http://i2.photobucket.com/albums/y29/Holescreek/Gunstuff/Fluting/x51flutes101010003.jpg

http://i2.photobucket.com/albums/y29/Holescreek/Gunstuff/Fluting/x51flutes101010005.jpg

A properly fluted chamber will have fairly consistent grooves beginning .07" in front of the cartridge and continuing for 80% of the cartridge length.

http://i2.photobucket.com/albums/y29/Holescreek/Gunstuff/Fluting/stainlessbarrel012311.jpg

Richard Erichsen
07-06-2012, 7:25 AM
With regards to your brass, notice the transition in flute width at the bottom of the shoulder transition to the sides. The flute width at the neck is so wide that the brass has flowed into it blocking off the gas flow, what does make it past is meeting the narrowed passages at the side transition.

I concur. FYI it was Wilson that made the JLD and early PTR barrels until they switched to Thompson Center, a move that supposedly coincided with resolving the specs Thompson was using for manufacturing the new barrels.

The pics you included really help to show the differences at the neck between incorrect and correct flutes. What I'm not able to explain satisfactorily is why a later serial number PTR would have a barrel with the same defects as the earlier models before those chronic chamber flute problems were supposed to be resolved. In any case, it's a warranty issue at this point.

To the OP, that barrel needs to be popped out and replaced with a properly fluted barrel. Regardless of the serial number and manufacture date, that barrel is a lemon. PTR has a habit of using parts on hand to build those 3500-4000 rifles per year and it's possible they accidentally used a barrel that may have been pressed out from a warranty repair on a new build, which would at least explain where a barrel with the wrong chamber flutes may have gotten into a new rifle. They have done the same thing with barrel pins, trunnions and who knows what else.

R

TacoJockey
07-06-2012, 8:39 AM
Thank you for the pics of the correct flutes, that really is an eye opener. I'll be sending this one back to PTR, thanks for all the help, I will update when I hear back from them. BTW, I am assuming I can ship the rifle to PTR myself, but can it be shipped directly back to me or does it have to go through an FFL?

Richard Erichsen
07-06-2012, 10:24 AM
Thank you for the pics of the correct flutes, that really is an eye opener. I'll be sending this one back to PTR, thanks for all the help, I will update when I hear back from them. BTW, I am assuming I can ship the rifle to PTR myself, but can it be shipped directly back to me or does it have to go through an FFL?

My understanding, even in this wretched state, is that you already own it and so no FFL is needed.

R

TacoJockey
08-22-2012, 10:00 PM
So I received the rifle back from PTR today, they had it for 4 weeks, plus 2 more weeks in transit.
I thought I was looking at a new gun when I opened the box. Their packing slip only states that the rifle was repaired as needed, but not what was fixed. As far as I can tell, the following was done:

-Receiver reparkerized (I'm guessing there was more to it than just a refinish job)
-hammer polished
-new bolt head
-ejector polished
-new bullet button (I was surprised at this)
-bolt carrier polished on bottom rails
-possible new barrel and trunnion - I expected a new barrel and I see no signs of wear on this one, so I'm guessing its new

I'll have it out at the range this weekend with the same american eagle ammo it choked on before, plus some reloads. Will post back after, hopefully all goes well....

DIRTY HARRY
08-22-2012, 11:11 PM
PTR WAS GOOD TO ME. AFTER 50 ROUNDS MY BOLT BLEW UP. I SENT IT BACK THEY MADE GOOD ON IT. AND IT SHOOTS BEAUTIFUL. BILLY

Richard Erichsen
08-23-2012, 5:52 AM
PTR WAS GOOD TO ME. AFTER 50 ROUNDS MY BOLT BLEW UP. I SENT IT BACK THEY MADE GOOD ON IT. AND IT SHOOTS BEAUTIFUL. BILLY

Your bolt did what?

R

crazychinaman
08-23-2012, 6:35 AM
PTR had a bad batch of bolts awhile back the where defective in the castings.

chead
08-23-2012, 7:56 AM
PTR has awesome customer service, they should take care of that for you.

someR1
08-23-2012, 8:06 AM
well, at least they fixed it (hopefully). Could have been bolt/carrier problems. Report back after your range trip !

TacoJockey
08-23-2012, 9:09 AM
PTR WAS GOOD TO ME. AFTER 50 ROUNDS MY BOLT BLEW UP. I SENT IT BACK THEY MADE GOOD ON IT. AND IT SHOOTS BEAUTIFUL. BILLY

Do you recall what the date stamp was on the bad bolt head? IIRC my original bolt head was marked 06/11, but this new one is marked 04/12.

TacoJockey
08-24-2012, 6:51 AM
[QUOTE=mj1;9190741]Ten to eleven reloads on CAVIM brass. I think it was 43.5g of H4895 and it really smacks the steel at 600.
QUOTE]

On your spent casings, have you ever noticed brass flowing into the chamber flutes (like in the pictures of my brass), or do you only get the black fluting marks from the fouling, and no other deformation?

Richard Erichsen
08-24-2012, 7:32 AM
On your spent casings, have you ever noticed brass flowing into the chamber flutes (like in the pictures of my brass), or do you only get the black fluting marks from the fouling, and no other deformation?

I wish the images were larger, but the brass has faint "fluting streaks" which are mostly propellent and a bit of embossing from the flutes. The width is consistent from mouth to 80% of the length of the case - exactly what you want to see. CAVIM brass is NATO thickness as far as I know, which decreases deformation, if slightly. That would explain why he's getting 10 or more reloads. The softer brass commercial .308 has a hard time getting more than about 5-7 reloads.

R

mj1
08-24-2012, 8:22 AM
[QUOTE=mj1;9190741]Ten to eleven reloads on CAVIM brass. I think it was 43.5g of H4895 and it really smacks the steel at 600.
QUOTE]

On your spent casings, have you ever noticed brass flowing into the chamber flutes (like in the pictures of my brass), or do you only get the black fluting marks from the fouling, and no other deformation?

There is some flowing but it get presed out in the re-sizing when you use good brass. I use LC brass for .223. No problem and I also use 7.62 LC brass but I have only reused it five times or less.

http://img.photobucket.com/albums/v130/montereyjack/3bbd24fe.jpg

chead
08-24-2012, 8:25 AM
On the PTR .308 pistol I had the fluting would be embossed on the brass. That's normal, the .308 HK-patterns have really aggressive chambers. In fact, the GI model was introduced so it COULD shoot steel. The non-GI model is really more of a match rifle that only wants nice brass.

TacoJockey
08-24-2012, 10:00 AM
My reloads so far had been on LC and federal commercial brass, but the embossing seemed about the same no matter what casing or load was used. My reloads were made using TAC, BLC2,and IMR4064. I did notice the sizing die ironed the flutes out nicely.

TacoJockey
08-26-2012, 10:36 PM
Ok so I put 65 rounds through the gun this weekend without a single issue, 40 rounds of factory american eagle and 25 reloads. Each round ejected strong, at least 25 feet forward, the handloads probably beat that by 5 additional feet. The embossing of the flutes was more pronounced on the factory brass than on the LC brass used for the handloads, but not nearly as bad as it was before I sent the gun in. It also appears that the flute marks are a consistent width on the brass. I was shooting more for function than accuracy, but was able to make ragged holes at 50 yards using the irons, will shoot at a longer range next time out. All in all it looks like PTR got it right this time. Thanks to everyone for the help resolving this issue!

Richard Erichsen
08-27-2012, 5:54 AM
Ok so I put 65 rounds through the gun this weekend without a single issue, 40 rounds of factory american eagle and 25 reloads. Each round ejected strong, at least 25 feet forward, the handloads probably beat that by 5 additional feet. The embossing of the flutes was more pronounced on the factory brass than on the LC brass used for the handloads, but not nearly as bad as it was before I sent the gun in. It also appears that the flute marks are a consistent width on the brass. I was shooting more for function than accuracy, but was able to make ragged holes at 50 yards using the irons, will shoot at a longer range next time out. All in all it looks like PTR got it right this time. Thanks to everyone for the help resolving this issue!

Buy a port buffer to avoid dinging up the brass quite so much. Port buffers also make the brass easier to find. Instead of 25 feet away, how about less than 6 and in a fairly nice pile?

$25 from Robert RTG, also sold by Numrich's.

R

ott1
08-27-2012, 7:11 AM
Port buffers from Robert RTG are $35 now.

TacoJockey
08-27-2012, 7:17 AM
Buy a port buffer to avoid dinging up the brass quite so much. Port buffers also make the brass easier to find. Instead of 25 feet away, how about less than 6 and in a fairly nice pile?

$25 from Robert RTG, also sold by Numrich's.

R

Funny enough I actually have a port buffer on the gun, I'm kind of interested to see how far the brass would fly if I took it off! It does a great job of saving the brass from being beat up.

ott1
08-27-2012, 2:56 PM
I just shot my completed 91 and I get embossing on the necks with '80 Hirtenberger (boxer) and almost none with '79 FN (berdan). 30 rds of FN then 10 rds of Hirt with no problems.