CO2 when filled is very cold and as it heats up the pressure in the tank rises so it would blow burst disks or worse, also the regulator on an air tank wouldn't be able to handle liquid so you would need to replace the regulator with a standard valve off a co2 tank you wouldn't be able to fill that tank with air after
i don't know if the co2 would do any damage to the air tank itself but at the end of the day there is a reason that air and co2 tanks are designed differently and it's not worth risking serious injury by trying it
Sorry just saw title and didn't read the rest sorry
Aaaaa so it's the reg :s As the co2 would not get to 4500 psi as it would turn into liquid way before that. Also the fiber wrap wouldn't be able to handle the cold as i also was worried about.
Just thought i'd ask as i've never used co2, always hpa and i can get a hold of co2 thats all.