Umarex I've gone through a dozen CO2's trying to load two different bb pistols in 2 days.....HELP!

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Bluemill

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Mar 14, 2023
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Scituate, MA
A couple of months ago I was thrilled by my newly found ability to make replacement CO2 seals for my old style Walther PPK/S pistol from Umarex. They cut and went in easily and the cartridges would last a good long time, and I could put two to three cartridges in before needing a new seal. Maybe I need a harder Polyurethane sheet- like 90 Durometer?

This weekend has been a disaster trying to load the above mentioned pistol, and an even newer one, a second generation (2016-23) PPK/S with the flush piercing screw. Both previous seals were not holding gas when trying to load a new tube. Each time once I heard the small hiss of a puncture, then I'd tighten the screw and things would quiet down a bit, then progressively the hissing would come back loader, until it was a full on discharge, with the frozen cartridge and all. There have been no traces of gas coming out of the barrel at all. I tried different inner and outer diameters for the seals, RWS Chamber Lube, Crosman Air Gun Oil, Silicone grease, Bars Leak auto transmission sealer, and even surrendered to trying Plumber's tape on the end of the tubes- all ending in the same hiss- Hiss-HISS, HISSSSSSS failures. I tried tightening the piercing screws on both guns, fast, slow, and as softly OR as hard as I dared for fear of damaging the bottom of the frame of the gun.

The only difference is the temperature in my basement now that it is fall. Instead of high 60's or even low 70's down there its in the lower 60's now. This has not been an issue last late winter or spring though. I am totally stumped. Any ideas? HELP!

Bluemill
 
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Bluemill said:
A couple of months ago I was thrilled by my newly found ability to make replacement CO2 seals for my old style Walther PPK/S pistol from Umarex. They cut and went in easily and the cartridges would last a good long time, and I could put two to three cartridges in before needing a new seal. Maybe I need a harder Polyurethane sheet- like 90 Durometer?

This weekend has been a disaster trying to load the above mentioned pistol, and an even newer one, a second generation (2016-23) PPK/S with the flush piercing screw. Both previous seals were not holding gas when trying to load a new tube. Each time once I heard the small hiss of a puncture, then I'd tighten the screw and things would quiet down a bit, then progressively the hissing would come back loader, until it was a full on discharge, with the frozen cartridge and all. There have been no traces of gas coming out of the barrel at all. I tried different inner and outer diameters for the seals, RWS Chamber Lube, Crosman Air Gun Oil, Silicone grease, Bars Leak auto transmission sealer, and even surrendered to trying Plumber's tape on the end of the tubes- all ending in the same hiss- Hiss-HISS, HISSSSSSS failures. I tried tightening the piercing screws on both guns, fast, slow, and as softly OR as hard as I dared for fear of damaging the bottom of the frame of the gun.

The only difference is the temperature in my basement now that it is fall. Instead of high 60's or even low 70's down there its in the lower 60's now. This has not been an issue last late winter or spring though. I am totally stumped. Any ideas? HELP!

Bluemill
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Bluemill said:
Each time once I heard the small hiss of a puncture, then I'd tighten the screw and things would quiet down a bit
Click to expand...
Does this screw essentially control how hard the nose of the cartridge squeezes against the seal? Reason I'm asking, I'm wondering if the thickness of the seal needs to be different. But if the screw compensates, at least within some reasonable limits, that can be removed from consideration.

Another question...when a seal fails, what sort of damage does it have? A close-up photo might be helpful.
 
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well, that is disappointing.
so if it was a Hammerli 850 that uses 88gr cart the Oring would seal the neck of the cart
but if it was Gamo R-77 pistol it would seal on the face of the cart and all the Gamo uses is a thin piece Urethane at 8.5mm OD 3mm ID 1mm thick they are either 70 or 90 dura
now i know you are trying to make nose sealing homemade seals
but this pistol has a history of cart sealing problems and as you have in the past just bought new valves because you could not find seals and or the price difference was not worth the hassle.
now on the oil lube whatever, it is not there to help seal but to lube the valve and it blown out as fast as you put it in
now the green seal show above are for some guns but they are one sided and not for this pistol and at there price i don't think worth it
now it appears that the 2 ppk's use the same seal and there is no other cross usage and the only poor picture is at
https://spares.bagnallandkirkwood.co.uk/product/part-22-umarex-walther-ppk-ppk-s-co2-seal-clear/
seeing that i am a stubborn SOB i would try something else, on the other end of the spectrum i might stuff those pistols in a box and buy something new
if you changed the piercing pin that would take the green seal or say the Walther 88 or 99 seal but that would only work if the area was the same size, i have 99's that could be measured
 
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This is a fabulous site with very supportive, knowledgeable, and responsive members! Thank you all for your responses. To Doomrider: I appreciate your opinion on Umarex and think they are very WEAK with their product support, especially with parts. Conversely, they have provided a lot of fine air pistols that no other company has at reasonable prices: Smith and Wesson Model 29, Makarov Ultra, and the Beretta 84FS.

To NervousTrig: I'm not giving up yet and your coaching has been much appreciated and indispensable ! The failed seals look quite good, but the piercing holes look larger and there is a small impression of the butt of the CO cartridge. When I first made the seals the CO would go in silently, and I'd shoot the gun to see if I'd punctured- and it had. To Marflow777: You are a Primo Techie/Smith! Thanks for your support and direction to B&K in the UK. I already did an order with them for the PPK seals. Today I'm going to try several different ID seals at 9mm OD- which I used with those first very successful parts. If that doesn't work I'll just wait for the B&K order from across the pond. I'll keep you posted friends.
 
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the thing is the seal has two sides and that might sound strange but both sides have to seal
the green seal that was mentioned it has a very interesting back side that fits what it is sitting on
the Gamo R-77 seal is just a flat piece of urethane
so when you take some sheet goods and punch out circles, is the piece pin also flat and if it is not then the pressure you put on the cart is all you have to seal the bottom, whereas the cart is sealed to it's side
and here is the rub CO2 gun have been around long enough that a manufacture standard seal could be used but no let's have 20 or 30 different ones, let's charge 8 bucks for 10 cents worth of material
if i had the model pistol i would be doing the same thing you are doing, making a better mouse trap, it is part of the hobby
 
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Those Green seals seem to hold up well and load the carts easily. The Umarex Model 29- 44 Magnum A la Dirty Harry uses them as does both the Beretta 84FS and the Makarov Ultra. I have had both latter pistols for several years with no signs of failure and loading goes well too in the drop out mags of bbs and CO2/combined.

I got nowhere today with the PPK cart loading fiasco. I stuffed 9mm OD cut seals into an 8mm retaining collar with 3, 3.5, 4, and 5mm ID gaskets. All failed exactly in the same fashion- just like yesterday. I just can't figure how just a few months ago the home made gaskets worked so well both in ease of loading and time they held gas. I'm punting then and will wait for the 3 PPK gaskets from B&K for an estimated $50, not knowing what they'll do on the exchange rate. I'm thinking I will likely end up just waiting for a nice new design of the PPK - perhaps a PP, from somebody. Wouldn't bother me if it were Gletcher as their stuff is pretty nice!
 
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but the piercing pin is just there to open the cart and if it does that it is doing it's job
the plain truth is there is a seal another gun uses that will work in your but to find it is the problem and the price of those seals is absurd at best
the problem i have in all my searches is a picture of the seal itself and i know they were pictured on the UK site but the picture makes little sense because it appears that they seal no the side of the neck vs the end of the cart
i was even looking for one of these pistol today to buy to play with the seal
i have 1mm and 3mm urethane sheet goods
the seals are never seen as new only after use
you see now i have more than a curiosity
i spend a lot of time on a UK forum and a guy had a question could you build the bottom half of a HW75 grip frame and use 1911 grips and so i started building one and helped him with his build, an idea, R&D and a proof of concept, a working model and yes it was possible
you are do the same thing but is it the material or something else
i will be reading along

mike in Washington state
 
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I will send you pictures of the used seals that were in the 2 different PPK's tomorrow. They measure 2mm thick, although they are deformed by the compression of the cart. The not quite round, oval holes measure 4mm. and the polyurethane seems about as hard as the 80 durometer sheet I have been using. They appear to be dished in to better seal the gas in. The home made seals worked great the first 15 times I made and used them. It's quite Bizarre they don't work now and a big mystery to me.

George, near Boston
 
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Is it possible a small piece of your seal got shaved off and has gotten into a position that it won't allow for proper sealing? The ovalling(?) suggests that the replacements are sliding around the piercing pin for some reason.

I have a Sig Sauer M17 mag that the seal failed in the passthrough valve and nothing I have tried has worked for it. Can't get replacement parts from them either, but they did make good and send a replacement mag fairly quick.
 
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I got lucky on a hunch today and was able to repair both my PPK pistols. The cartridges went in easily and the 2nd series one was silent - no hiss at all, but when pulling the trigger there was an authoritative POP.

About 2014 or so the Japanese subcontractor who made the pistols for Umarex started punching the side of the air valves to lock the brass retaining collars in place. Prior to that they were only hand tightened, and these brass collars held the Cartridge gaskets in place. I found that I could remove these collars, but when doing so the threads were damaged a bit each time they were removed or installed due to the punches- see photos below.

Apparently this thread damage caused gas leaks and made it impossible to have a tight seal- and lose yet another CO2. What's weird is that both guns had the same cumulative failure at the same time.

Having bought my first Crosman/Walther PPK in 2002, I had accumulated several air valves to fix leaking gaskets. I saved the old parts and they did not have those troublesome punch marks. I disassembled two internals of the damaged valves and transferred the parts to the valve bodies that were punch free. It was still just a hunch... but I did both guns prior to testing- no big deal I could do it blindfolded now I think....(20 X?)

So it was NOT a gasket problem- they are fine. I've got bunch of partially used gaskets now, but more importantly, I finally solved the mystery leak, and I got both guns back!

Yours,
Bluemill

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The brass collar is the only chaser I could use and it doesn't stand up well to the steel of the valve body (I think?) It is a very fine thread and likely an exotic pitch. The inside of the valve when you look at the threaded area is devoid of threading where the punches are. This a.m. one gun was fine the other, the newer Gen 2 gun was almost out of gas. Today I'll cut a new gasket and put some BLUE (medium) thread lock on the brass collar prior to installing. This is my way to secure it while installing & uninstalling co2, but also to ensure that the brass collar that might be damaged is airtight. It's pretty easy to damage the brass collar- either by the threading or crack it at the narrow neck area cut in the piece to allow you to unscrew them. Finally figuring the big leak out was very satisfying!
 
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and the seal goes under the brass retainer or on top
i did watch a video and the guy was putting the seal on the inside of the retainer and i thought it was odd
i wonder if a Crosman seal for the 2240-2300 valves would work G397-012 now some people sell them for 6-9 bucks but they about 2 bucks
the material would be right, they are flat type, cut from sheet good
and if the retainer was staked, they did not want you to remove them, nice little pistol stupid manufacturing
 
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There is an indentation lip that perfectly fits an 8mm diameter seal at the bottom of the retaining collar. That lip is like 2mm deep so the seal is flush with it as the seal is 2mm thick and makes it a possible gas leak point. If the seal were 2.5mm thick or even 2.25mm it would be better I'd guess.
Where is the video you are writing about? Also can you get the seals from Crosman? They distributed the first PPK bb guns in 1999. I still have my original slide that has Crosman embossed on the right side. Maybe I could bounce it off of them for ideas as they once sold the product.

The Crosman 357 pellet pistol is still one of my favorites. I know it looks very unauthentic, perhaps crude, BUT its strong points more than make up for its looks. Those points are: 6.25" RIFLED barrel, 400+ muzzle velocity, decent double action, 10 round clips that can be readily changed and are portable, and a Fully Adjustable rear sight for height and windage. If there is a varmint in the yard that needs a lesson this is the pistol I get out! Also the price is right for all that performance. Not sure these are still sold but the "Vigilante" looks to be similar.
 
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