Suppressor Legalities
Remember kids, when it comes to sound suppressors that the suppressor itself is regulated whether you put it on a BB gun or a paintball gun. If you put one on a BB gun or paintball gun and don’t pay a tax, it’s illegal unless the suppressor is permanently attached to the non-gun or cannot be used on a real gun or removal from the non-gun would render it inoperable.
Update: and, in the eyes of the law, a suppressor is a firearm.