Paintball guns fire paint balls by means of a bolt that pushes the round, or paint ball, forward from the firing chamber. This firing bolt can be powered by either compressed air, nitrogen gas or carbon dioxide (CO2), which is stored in tanks that usually attach to the rear of the gun above the pistol grip and below the hopper. Smaller carbon dioxide cartridges are available that make the gun lighter and more maneuverable, but these cartridges provide power for only about 10 shots. To gain the advantage of being able to fire hundreds of shots per cartridge, you can use a compressed air tank filled with carbon dioxide.
1. Wait until the tank on the gun is completely empty. Removing a tank with carbon dioxide still in it is wasteful and can be a tricky procedure.
2. Remove the hopper or drain it of paint balls. Do not recharge the paint ball gun while it is still loaded.
3. Discharge any remaining paint balls by pulling the trigger while the old tank is still attached. Any balls that slipped into the firing chamber will be fired, emptying the gun completely.
4. Detach the empty tank by screwing counterclockwise, and replace it with a full carbon dioxide tank, screwing it clockwise into place. Tighten until it is snug and secure, but do not overtighten, which can strip the threading and ruin your seal.
5. Use the paint ball gun for several hundred shots, powering the bolt with the compressed carbon dioxide gas. When it has emptied, simply replace it again.