> Study traps.... then what? Trap it? And then what?
Animal control will probably be much more prone to come and take a dog if is trapped in a room or a cage. Your mileage may vary depending on the area or country. If they take the dog, the dog owner will need to pay for the dog maintenance at the time of recovering it.
Moreover, if you shoot a pitbull and fail, most probably will try to attack you. This can end very bad for both, you and the owner of the dog, so probably not the wisest move. This dog can kill a person, and shooting him in a leg for example assures that will have the motivation to try