I agree with Mike.
A little compressor is the way to go.
Co2 is something whe should not be using to much anyway cause of the enviroment.
Haven't your paintball clubs switched over to compressed air yet?
Here in Holland Paintballers use the same size tanks but with compressed air these days.
I have to get my tank altered so it can take the compressor nozzle at the local diving store and fill it with air rather thenn co2.
I could fill the tank at this diving shop or at the paintball shop and probably even at the firefighter station.
Just my 2 cents
