IMO weapon regulations should follow two main categories,
Loading action and holding class, IE how the weapon prepares the next shot when fired, and if it's designed as a one handed or two handed weapon.
A pump action rifle needs different regulation than a semi-auto pistol, and frankly should require different licenses too, getting good at martial arts using a kitana does not qualify you to enter a duel using scimitars.
Yeah, the one thing I'd need to look into more is say the difference between a shotgun and a single shot rifle, IDK if scattershot is a class unto itself or if "two handed manual action" is enough categorization for proper regulation