The engineering and physics involved in building/tuning guns and shooting accurately is very interesting.
Furthermore, the "renegade" spirit required to reject the status-quo and push the envelope in science and engineering attracts quite a few of the same types of people.
Finally, the idea of "banning" guns -- which every basically qualified engineer or physicist should be capable to building from readily available materials and tools -- makes them even more interesting. If for no other reason than to illuminate preposterous and insulting nature of the idea.
IMHO. ;)