You take a piece of any type of ammunition and fire it the means by which it should be fired. If you whistle in a certain pattern you can change the direction and speed of the thing that is being fired at the target.(cannot completely stop it, must be going at a discernable speed) An extra piece of ammo appears and, when fired, moves around all obstacles in order to strike the target. No matter what ammunition you use, roll a d10 piercing for each piece of ammunition. For this to work your character must be able to whistle.