Things You'll Need
Instructions
Find a water gun that uses a pump action. The bigger the gun, the more powerful your BB gun will be.
Locate a small metal tube that is the size or a little larger than the BB and about 6 inches long.
Attach the tube to the nozzle on the water gun. Hot glue the tube to the water gun nozzle and hold in place until glue cools and hardens.
Drop a BB into the tube. Pump the gun and fire. The pump is located underneath the trigger. Pull it out and push it back in until it becomes hard to continue. The more times you pump the weapon, the faster the BB with expel from the tube, because there is a great deal of air pressure built up.
Pull the trigger while facing away from people, cars and homes. Make a target from household items and get to practicing. Show your friends how they to can make their own air-powered BB gun.