i am able (and do) own a shotgun and i can do a hell of a lot more damage with that than a 9mm handung
Here you are allowed to own large-caliber firearms when you are 21 years or older BUT you have to go to a shrink to pass a psycho test to determine your mental health and stability required by law for future firearms owners.
Or you wait till you're 25 years old. Then no test is necessary anymore, because our pols declared that those persons are "sane, reliable and mentally stable" by virtue of age.
As always, my advice - delivered in true Army of Darkness style - is "reload, baby".