TargetTalk

Should I leave the CO2 cylinder screwed tightly onto the pistol
(like when it is being fired) during storage or should I back it off so that
it is still attached but loose? I suspect that leaving the seal on the CO2 cylinder compressed will shorten the life of the seal. Maybe it makes no difference! I keep the Walther CPM -1 in it's case and in a safe so I don't think dust entry will be a problem. I intend to dry fire the pistol 4-5 times per week and shoot at least once per week. Any advice?

I only remove the cylinder on my PCP pistol if I'm going to store my AP for a an extended period of time without using it (a month or so). Not sure if there is any difference with CO2, but the most wear and stresses on the o-ring comes from the friction while tightening it.

These cylinder O-rings are under pressure and subjected to abrasion when opening, so I also try to avoid doing this more often than necessary. This also means that I try to avoid refilling more often than necessary. This O-ring stuff is really not very good design, but they are all like that both CO2 and PCP. I have a CPM1 that has not been shot for a couple of months, and I see no reason to take it apart. So if you shoot it every week, don't worry.

OTOH O-rings are not very expensive, but special O-rings for CO2 may be hard to find if you don't have a suitable supplier.

Thanks for the input. This all makes sense to me. The range master at my club had me unscrewing the CO2 cylinder on the club FWB c10 I was using up until I bought my Walther last week. Thanks again.

I think this thread has been touched on before, but somewhat inconclusively.
I have been of the school that removes/unscrews the tank after each session. This allows me to keep track of the CO2 level with a small digital scale. Two things to keep in mind are thread and o-ring lube - think moly and silicone. To minimize thread wear (Walther uses brass against brass - tank to gun probe - in all the CP and CPM series) I unscrew the tank one to two turns (in order to unload the poppet pin), make sure its unloaded, and fire the pistol five to six times to relieve the CO2 pressure in the gun. Then completely unscrew the tank. WONDERFUL no gas pressure load on the threads!
Sounds great doesn’t it.
Last week I did this and just past the 11/4 turn, the tank blew off, stripping the threads on both tank and bulk tank adaptor (which, I think, had an undersized thread major diameter).
I guess now I’m a member of the other school that leaves the gun pressurized and stocks up on valve seals for the gun and the tiny (-004) o-rings for the tank.

ghilt

i need to find a fill adapter for this walther i got this pistol but the adapter to fill the 2 tanks is gone. anyone know were to get parts? thank you.

Two places that I can think of are Earl's Repair or Walther

I have this model and have wondered about this myself. The seal in the pistol itself is cheap, so if it stays under pressure for a long time and fails, it is easy to fix. On the other hand, the seals in the valve cannot be purchased so the entire valve needs to be replaced ($60 ea.). I had to replace two of these last year, and was forced to send the cylinders in. I could not purchase the valves and replace them myself. This might discourage me from purchasing a Walther in the future, if not allowed to work on it myself. Otherwise, I think they make a good product. Have had mine a long time and shot some respectable scores. For long term storage, I think the cylinder should be empty and lightly attached to the pistol to take the pressure off the valve seal. I am not sure what Walther recommends but it would be interesting to know.

BEA brings up a good point. Current authorized agent (CAA) does charge $60 for tank work and "resealing" appears to consist of one rather small o-ring. OEM ring appears to be mertic as well as polyurethane. Right now I'm trying a -004 EDPM o-ring which set me back about 50 cents from The O-ring Store. After two weeks, its holding CO2 - time will tell. CAA also wanted the entire pistol sent to him for tank reseal and quoted "manufacturer's requirements" when challanged about this on the phone.
But I still love my Walthers!!

Where did you purchase the small oring for the cylinder valve? Is the number you provided the size? What about the larger black oring on the outside of the valve, did you replace that too?

The place can be found at: www.theoringstore.com (aka O-Rings, Inc, Los Angeles, CA 323-343-9500). The small ring which fits on the valve stem is -004 E80 and the larger is -021 E80. The numbers appear to represent the size and 80 durometer EDPM rubber. The larger one is a static seal and is probable in good shape but while the tank is open....

A couple of observations:

Availability of adapters:
Walther used the same attachment hardware on both CO2 rifles and CO2 pistols. At least the CPM1 and the CG90 can use the same fill adapter.

I keep track of the CO2 level by weighing the complete gun. Most digital kitchen scales with 1 gram accuracy go to 2 kilograms which is enough to do this.

Normal hardware store O-rings will swell just like a sponge when subjected to CO2. This may work OK for a while for permanently attached parts, but not for moving things. The sweling will go back after a while in free air.

SCUBA divers always keep their tanks partially filled during storage to guarantee against moisture entering the tanks. I think this is a generally good idea.