Hpa tanks

[Gen0cide]

Do you need to use a HPA tank with a WGP pro stock 04 or can c02 be used without damage to the gun?

[Ezero06]

u could use co2 if it's anti-siphoned but its not really recommended. i would go with an HPA tank

[V1nn`/]

Theres some threads already on this. If you use CO2 in a gun all it will really do is give you velocity spikes, big white clouds, and wear your orings out faster. Do a search in the New Paintballers section and youll find pages and pages of this information.

Its always a good idea to run N2 in a cocker just because you dont have to worry about orings, and freezing and breaking your front block. Also if you plan on upgrading your gun later on its nice to have a N2 tank. If you do get a N2 tank make sure the preset pressure is LP which is like 350-450 psi. (Cockers run on LP tanks, older angels, timmys, spyders and other guns use HP presets)

EDIT: Here is from this section. I'd also suggest looking in the Air Systems section.
http://www.pbreview.com/forums/showthread.php?s=&threadid=300208