"In a perfect world..." as determined by you, an imperfect entity. I'm sure you're perfectly capable of educating me as to how I'm an abhorrent and irresponsible person because I own a variety of firearms which you deem "unnecessary".
Who are you to decide what, how, and how many firearms people are allowed to own? From where do your statistics and/or reasoning derive? Do you realize that there are semiautomatic, rifled, "high capacity" shotguns as well? Would you limit them only to pump-action, lever-action, breech loading or otherwise? What would the capacity be for a magazine?
Please, define some limitations without tossing around arbitrary figures. Is a firearm with more than X rounds more capable of killing than one with Y fewer rounds? Once the magazine is expended, couldn't you simply reload? Does the size or caliber of the weapon itself define its lethality? Is a .22LR not as capable of killing as a .50BMG?
My point is that the arguments you're providing are all moot. You would place restrictions on the very freedoms which Americans enjoy, at what cost? What would your restrictions effectively accomplish? They would not reduce crime. They would not reduce negligence. This would merely limit the capabilities of what your average person is able to enjoy and own in a legal manner.
It is not about necessity. You don't need a car, a phone, or the internet, yet you use those -- I'm giving the benefit of the doubt in assuming you do this without harming anyone else in the process. Those are not constitutionally protected liberties; notice that I did not say constitutionally granted liberties. Firearms are, and for damned good reasons. If you choose not to exercise them to any extent, then that is your prerogative.