The firemen had it licked until they backed right into the bender's front cannon. The firemen had had better cannons but they didn't do a good job of keeping the target away from the enemy.
As far as paintball cannons.....a good friend of mine uses one of my small t-shirt launchers as a paintball shotgun. He stuffs a rag down the barrel, dumps in 250 paintballs, and stuffs another rag in the barrel to keep the balls from rolling out. He can take out an entire squad with one shot.
As for paintball tanks.....check out my links page. I put up a link to one of my customer's sites. He used a supah plus for the main valve in a paintball tank that he and his buddies built. TONS OF GOOD PICS!!!!