advice on starting up an old CO2 pistol and tank?

[Hamster]

Just bought a nice looking Walther CP2 air pistol, complete with a fire extinguisher style tank, 2 grips, tools & thankfully a manual. My first nice air pistol. Said to be an estate item, unused for the last ten years. Last competition sticker is dated 2007 (British Columbia Air Gun Championship). Tank inspection card also 2007. The tank expels gas strongly, and by weight it's about half full. (The full and empty weights are helpfully noted on the tank.) I understand how to fill it (cool the cylinder and add 53g of CO2). Any reason not to use the old C0 O2 in the tank now? Sold by a Cowboy Action oriented gun store that knew nothing about it. It's a little heavy and old school but I kinda like that.

[hurt]

It is a good pistol..very capable. A little heavy...but that suits me too! I add weight to everything I can. I can’t imagine that CO2 has expiration?? Good shooting

[Rover]

Just use the CO2 in the tank. RE: Inspection....when tank is empty take it to a welding supply shop and have them trade it for another (full) one. Cost probably around $15C.

Don't get detail-crazy when filling your cylinder. Just stick it in your freezer for 5 minutes or so, then fill. Close enough for government work.

[Gwhite]

The best CO2 tanks have a siphon tube that goes down to the bottom so you get liquid & not just gas. If you don't have a siphon tube, you can get a moderately good fill by cooling the cylinder more. If your CO2 tank is small enough, you can also lift it up so the liquid CO2 can flow down into the cylinder. if you do this, be careful. It's often possible to get more CO2 into the cylinder than the max weight, and you should vent it just to be safe. I don't know how much liquid CO2 expands when it warms up, but there is a small risk of a ruptured cylinder if it's completely full of liquid.

[Hamster]

Thanks to all for your advice. The only point I'm unclear on is how to vent gas from the cylinder if I overfill it. Would be grateful for any comment on that.

[Gwhite]

I thought that you could just screw in the fill adapter to vent excess CO2, but the manual mentions a "gas discharge nipple", which fits over the end of the fill adapter. It looks small enough that it has probably gotten lost long ago.

If my memory is correct (not necessarily a good bet these days...) you can probably open the valve with almost any small pointy plastic object. Just wear a glove to avoid freezing your hand. The cap on a cheap BIC pen should work.

[GaryN]

I would not try to invert a tank over 5 pounds, without a rack to hold the tank. Inverting a 10 pound tank was scarey.
Which is why it is better to use a small tank, if it does NOT have a syphon.
Then as was said you just exchange the tank for a new filled one.

With a large tank you really want a syphon.
But with a syphon, you have to OWN the tank, as you will lose the syphon if you do an exchange.
Then you have periodic pressure/hydro test to have to do on the tank, before they will refill it.

I put the cylinder in the fridge, NOT the freezer, for about 5 minutes.
That cools it down enough to get close to a full fill, without overfilling.
You have to determine what works for YOUR cylinder and fridge.

Get a decent kitchen scale that measures in single grams.
Some will measure in increments of 5 grams.

Also wear eye protection if you try to vent the cylinder.

[Gwhite]

The team I help coach has had no problem getting 20 pound tanks with a siphon tube from the local Airgas dealer. We exchange them when empty, although they are scarce enough that you need to call to make sure they have one in stock. That said, 20 pounds of CO2 is fine for a large team, but it's a lifetime supply for an individual. When I shot CO2, I used a 5 pound tank.

[JFuller]

As you are in British Columbia just thought I'd mention that Northern Ropes quoted me $70 to hydro statically test, install a dip tube (syphon), and refill my 20lb tank.
I was told that CO2 should also be available in Abbotsford for the Provincials on the Victoria Day long weekend in May, see you there. John.

[Hamster]

One more question, about alternatives to the old red fire extinguisher tank I acquired with the pistol. It's close to empty and will be expensive to recertify at the local fire supply store (needs hydrostatic test they say). Having been stored near empty for years I'm worried it's not clean. So I'm wondering about a new paintball or home brewing CO2 tank instead. I looked at a 20 oz paintball tank down at the local big box store. The brass fitting on top has has the same threads as a fire extinguisher, so my Walther adapter will fit, but the paintball tank has no obvious control valve to turn the flow of gas off and on. It just has a tiny pressure blowout valve. Home brewing CO2 tanks apparently do have a control valve and look a lot more like a fire extinguisher, just lighter (and cheaper, with food grade CO2). Aquarium stores have similar tanks too. So maybe these can be used as-is. I'd welcome any tips on how to use these sources to feed a pistol like the CP2. I have not managed to fill the pistol yet, but eager to use it.

[stephen_maly]

If the CO2 tank was owned by the same person who owned the gun, chances are that it is ready set up to use. It will need to be tested before it is refilled (that's the law if the previous pressure test is more than 10 years ago). You need to keep the cylinder from the pistol cooler than the charging tank, or the CO2 will not flow. Make sure that the cylinder is the correct weight (or less) before you go to shoot with it. It will not rupture if it is overfilled, but the gun will not work properly because the back pressure on the valve is too great. If you need to remove some CO2 from the cylinder, use the adapter (like GWhite suggested). CO2 was replaced because it was a pain-in-the-neck to refill. A compressed air PCP system is mechanically more complicated (you need a pressure reducing regulator), but you can refill a partially filled compressed air cylinder. This process is more difficult with a CO2 cylinder. If you can get a hydrostatic test and refill for $100 CDN, just do it. That amount of money might get you six tins of good pellets (if the tax rate is low). I still have a 3/4 filled 20 lb CO2 tank in my basement. I stopped using it about 20 years ago, and never looked back.

[Rover]

I don't know what the difference in regulations are between US and Canada regarding testing, so....

Take the tank to a WELDING SUPPLY shop. They will just exchange it for a full one.

You needn't worry about corrosion in the CO2 tank since there is no water in it.

Don't exchange tanks until it is EMPTY. It's not like air, that needs a refill when less than half empty.

You will get perhaps twice as many shots (well over 200) on a CO2 cylinder fill compared to air.

Put cylinder in freezer for FIVE minutes before filling; it won't overfill---just slap it on the gun and shoot.

[northpaw]

You needn't worry about corrosion in the CO2 tank since there is no water in it.

Well, hopefully.Pressuretesting of the thank is performed by filling it with water, then pressurize it. The test pressure in my country for a CO2 tank is 175 bars. If some lazy, or ignorant, operator at the shop does not fully dry out the interior of the tank properly, with dry air, then some water may remain in the tank. Interior corrosion may follow.

Don't exchange tanks until it is EMPTY.

Not quite empty, but to a point when there is noe more liquid CO2 in the tank. This appears when the clynder from the gun will not show full fill-weight after a filling.

How to avoid overfilling: Leave the cylinder in the fridge for some time, not in the freeze. Overfilling is probably the main cause of leaking cylinder valves, IMO.

[Gwhite]

When I got a Walther CP1 around 1982, I bought my CO2 tank specifically from a medical/industrial gas supplier I could trust to give me DRY CO2.

A friend of mine bought one of the very 1st CP2's imported into the US. He got a "good deal" on a CO2 tank that had been used for carbonating beverages. Unfortunately, a common problem with beverage cylinders is that people run them empty, and they can get back-filled with water.

He ended up with the worlds most expensive water pistol. It took a lot of work to dry everything out, but he shot it for years without any issues.

[Hamster]

Thanks again to all for their comments. This fine old pistol is up and running and really a delight to shoot. And as others pointed out, the CO2 technology is really quite easy to use.

[F/V Icy Swan]

I understand these pistols can be converted to PCP. Has anybody done this? If so, who did you use, how much did it cost, and was it worth it? I am already set up with HPA compressor. I agree, these are fine pistols.

Mike

[Rover]

I understand these pistols can be converted to PCP. Has anybody done this? If so, who did you use, how much did it cost, and was it worth it? I am already set up with HPA compressor. I agree, these are fine pistols.

Mike

I think there was (is"?) a Steyr LP1 conversion kit available. You would also have to buy additional cylinders. There have been a few older posts on the subject. Do a Search.

I've also heard that older FWB CO2 guns could be used as is with minor alteration, but you would have the problem of charging the cylinders. Personally, I wouldn't bother with any of this as the CO2 guns are so good.

[Gwhite]

I've converted a couple of old Steyrs,but I've never heard of a conversion for the CP2. In theory, it's "just" a matter of installing a pressure regulator on the front of the pistol that a compressed air cylinder screws onto. Because every make of pistol's cylinder interface is different, such a conversion would be brand & often model specific.

[F/V Icy Swan]

Thanks for the conversion input. I am trying to keep things simple by not having multiple platforms, but that may not be best.

Mike

[Hamster]

Another question -- this old CP2 is working well, shooting accurately and consistently, but high. With the official ISSF 10m air pistol target at the correct distance, I find that I have to hold very low, below sub six, to keep my shots in the black. I've lowered the rear sight as far as it goes. Changing pellet weights doesn't make much difference. I've tried both 7.0 gr and 8.2 gr RWS Meisterkugeln. I'm new to air pistols but have enough experience with .22LR match pistols (at 25m) to be confident that I'm holding the pistol correctly. Should I try unscrewing and shimming the front sight to raise it 1 or 2 mm? And if so, what's the best material to use? I don't see any taller front sights available anywhere on line. I could have a machinist make one. I'd welcome any advice.