First attempt to make a small and powerfull BB gun. Drag the piston back and squeeze slightly on the beck of the tube to fix the piston. Load a BB bullet through the hole and release the grip of the tube to fire. In the barrel there is a small ring to prevent the BB bullet to roll out of the nozzle. WARNING. Dont shoot at people of animals. This thing is only for fun and for target practicing.Print in upright position in ABS. Set for fine and carefully add support in the hole for loading the BB bullet, and under the loading grips. Carefully remove support after printing and clean the slide. Then it works just perfect. File for Turbocad 3D included to those who want to design a good trigger and safety mechanism.