CO2 v Compressed Air

[BobSki]

I apologise if this is a very silly question, but why do pistols use CO2 or "soda-syphon" 12g cartidges instead of compressed air?

My line of thought has been prompted by stumbling across Steve's article on how to make re-fillable 12g CO2 cartridges. I do not have access to the necessary lathes etc he used in his article, so I doubt very much that I would be in a position to avail myself of the advantages he so abley demonstrates.

However, taking his process as an example, why could those same refillable cartridges not be filled with compressed air via a hills/FX stirrup pump or even a divers bottle. Does the CO2 contain properties that make it so much better than compressed air when used in a pistol?

Kind Regards
Bob

[Jerry Cornelius]

CO2 liquifies at moderate pressures at room temperature. Your 12 gram capsule is largely liquid. That means the gas above it will be at a constant pressure for given pressure.

This gives more shots at a consistent and moderate pressure than you can get with air. No pressure curve.

Or that's what I understood. The downside is greater temperature sensitivity, the pressures attainable are not terribly high (and cannot be increased unless you raise the temprature), and I believe the seals are harder to make, as CO2 diffused into many seal materials.

[Linnet67]

CO2 only gives constant pressure for the first 50-60 shots (depending on the gun) from the 12g cartridges and then drops off.

PCP is considered more consistent and is the 'norm' for competitive 10M pistol shooting these days, as you get far more shots from your standard PCP cannister ie plenty to shoot a whole competition.

ATVB
Linnet

[Jerry Cornelius]

PCP is considered more consistent and is the 'norm' for competitive 10M pistol shooting these days, as you get far more shots from your standard PCP cannister ie plenty to shoot a whole competition.

I know that all the top pistols are air now, but I've assumed that is because a bigger cannister and no doubt clever internals overcome the power curve of air?

My PCP rifle will give about 60 shots at good consistency, which makes consistent 60 shots from a little 12g cartridge look pretty good!

I suspect that the real answer to rattycatcher's question is "just because" . When the likes of crosman and co were starting out, I guess it was just easier to produce CO2 cartridges. Now we have dive shops and pumps its easy to get air compressed to pretty high pressures, but by now the 12g CO2 cartridge is a fact of life.

Plus I'm a lot less scared by CO2 at room temperature than I am by air at 200 Bar !

[gingernut]

Brocock made an air cartridge that looks like a co2 capsule. You use an air tank to put 240 pressure into it. You then get 25 higher pressure shots out of your umarex, Works well cost about £25. Must dig mine out and use it more. You do need an adaptor but eventually I suppose you might start saving money!
They may still have them at Brocock.

[gingernut]

PS. you can put air in a co2 gun.You cannot put co2 in an air gun it will wreck it and maybe you too.

[derekm]

PS. you can put air in a co2 gun.You cannot put co2 in an air gun it will wreck it and maybe you too.

Wrong way round, I think.

[Jerry Cornelius]

I wouldn't do either. CO2 will wreck the seals of an air gun. And as air can be compressed to far higher pressure than CO2, you'd have to be VERY careful running air through a CO2 gun not to overpressurise and blow the thing to pieces.

There are no circumstances at all that I would do either.

[BobSki]

Gentlemen, most informative, thank you one and all for taking the time to educate me, it is much appreciated.

Kind Regards
Bob

[gingernut]

Apparently nobody told Brocock they were wrong then!

[Craig-P]

Apparently nobody told Brocock they were wrong then!

I believe the Government did...

[Linnet67]

Gentlemen, most informative, thank you one and all for taking the time to educate me, it is much appreciated.

Kind Regards
Bob

How very sexist! What about the education from the gals

[cookie]

How very sexist! What about the education from the gals

Just cook my dinner, iron my shirt and do that washing up it's been there for hour's.

Hi Lynne, how are you honey? how's that Tau of your's, i'm expecting good things from you in the 3rd round of the 6 yard and 10m comp's. It's a shame you can't make the meet. we will just have to wait for the next one.

atvb

Jason

[Linnet67]

Just cook my dinner, iron my shirt and do that washing up it's been there for hour's.

Hi Lynne, how are you honey? how's that Tau of your's, i'm expecting good things from you in the 3rd round of the 6 yard and 10m comp's. It's a shame you can't make the meet. we will just have to wait for the next one.

atvb

Jason

Cheeky git.... I've got some ironing, you can do mine, while you're doing yours! Snigger

My Tau is still lovely ta. I thought my shiny new HW40 was pretty good straight out of the box today. Just the PCP to do tomorrow morning.

Yeah I'm disappointed about the meet, I was looking forward to a pink camo wooden spoon

Linnet67 x

[cookie]

I hope you do better with your HW40 than i did with mine, this was my target pistol for over a year, and today you would have thought i've never shot it before. oh well there's always next month.

atvb

Jason