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gage3780 · Member

What's the absolute minimum outside air temperature that you can fire you co2 gun. I've read 60 degrees Fahrenheit?

rsterne · Moderator

I have fired a CO2 gun that I took out of the fridge (about 3*C) and it still fires, but a lot less power, of course.... At 40*F the pressure is down to 567 psi instead of the 853 psi at 70*F.... That will reduce the FPE in about the same proportion.... a drop of about 1/3 in power....

Bob

gage3780 · Member

OK thanks for the info. With temperatures starting to drop I'm going to see how my guns perform in colder weather. Should be in the low to mid 60's F here and I'll see what happens and how they do.

AirGunEric · Site Admin

Look on the main page here for a Co2 temperature-pressure calculator:

http://www.airgunhome.com/

http://www.airgunhome.com/pages/calculators.html

-most airguns have traditionally been measured at 70*F for the advertised velocities, but I suspect like in most things there is alot of exaggeration.

If, for example, your Co2 pistol shoots a pellet at 430fps (i.e. like a Crosman 2240) at 70* (or 833psi on the Co2) at 32*F (freezing for water) the Co2 pressure drops to 506psi- i.e. almost a 40% reduction in pressure and likely slightly more in power (i.e. 430fps becomes 258fps which is virtually useless).

You can either 'fiddle' with it using the calculator and some estimating, or just experiment, but it's pretty safe to say any Co2-powered gun, no matter how high its rated velocity at 70*F (i.e. an 850fps Co2 rifle), is going to be essentially useless in any respect at anything under 10*F

gage3780 · Member

Thank you, I appreciate the info. Was out today firing a new BB non Blowback in high 50'sF and it shot good at 20-25 ft. I bought a cheap Umarex XBG bb to see how a non blowback fired. Supposed to warm up for a couple of days so I'll be trying this gun out.

icuppu · New Member

When I'm out in the field (back yard) and I'm shooting my CO2 BB gun with my back up hunting buddy (grandson), and I need to know the pressure of the CO2, I break out my 99 cent scientific calculator and plug in the variables (temperature in Fahrenheit) to get the psi.

Following is my rule of thumb formula that is off by a degree or two Fahrenheit, but close enough for government work.

100 x pi x e^(F/71.8) = CO2 psi

For example,

100 x pi x e^(83.134 F / 71.8) = 1,000 psi (not perfect, but close enough)

In case you need a certain psi, reverse engineering:

71.8 x Ln(1,000 psi / (100 x pi)) = 83.134 degrees Fahrenheit (Cool?)

From what I've read that most CO2 guns are rated or tested at 70 degrees Fahrenheit then using my rule of thumb formula would give 832.83 psi. Close enough?

AirGunEric · Site Admin

[quote="icuppu"].../quote]

Just use the calculator and save yourself some time: http://www.airgunhome.com/pages/calculators.html

Alstone · Moderator & Site Supporter

By using an electronically controlled Co2 tube heater I can shoot winter or summer at 800 fps down to 3deg F

Al

nvreloader · New Member

Hey Al

Would you care to provide the info on your heating system?

Looks like it might work on this side of the pond........ also. LOL

I have a Crosman 150 and 160 Co2 pistol/rifle,
that want to go play out in the cold, along with my PCP toys.........

Thank you,
Don