dangerous and unusual.
A "trained" man eating tiger is dangerous.
If legal mortars and RPGs would almost certainly not be unusual. If I could pick up an RPG for $500 as can be done in some parts of the world I would probably do it. Then I would buy a junker GM product and introduce the two. In a reasonably controlled environment with practical safety taken.
Yes I know it is possible to own a mortar or RPG, but restrictions have made them illegal practicaly speaking.