Just played paintball yesterday and i went through 29oz of co2 and close to 950 paintballs. I got a pocket full of paintballs worth a shots using the 9oz playing civil war!!! The balls come out weak even if the velocity is turned up all the way. I played with the velocity turned down so i was not using as much co2. I took my gun apart and from what i can see everything is fine. I thought the guys were ripping me off when they were filling my tanks but when I'm holding the charged gun the front hand gip seems to get cold. Could there be a leak in the powertube or in the fitting? If so are they hard to take apart and put back together or should i take it somewhere to get fixed? 

Enos Shenk wrote: A low co2 tank wont affect your shot velocity until the last 10 shots are so. co2 always outputs the same pressure regardless of how much is left in your tank, then the last few shots will "machinegun" when the tank is pretty much totally dry. So the gun recocks and operates normally except low velocity? Do you have a monstrously long 21" barrel or something? Thats one of the very few things that would cause that.

Yes the gun recocks and operates normally except the low velocity. I have put no aftermarket parts on my gun. The paintballs are fine, most of my friends have the 98 custom and use the same brand of paintballs.