The fact you can go hunting with a truck mounted machine gun doesn't suddenly mean that it should be legalised. I can eat dinner with a combat knife. It does not make it an acceptable thing to do.

Altering definitions to fit the current guns has been done in the past when machine guns were made illegal. The initial definition was something along the lines of a gun that has a continual rate of fire on depression of the trigger. Of course, someone made a weapon that fires the whole magazine on pressing the trigger once. The laws were quickly changed - without banning all guns!

Varying barriers to ownership would be another approach. You want a .22 pistol that holds 6 bullets? Relatively easy to get hold of. A desert eagle .50 with an extended mag? Possibly some more information is needed, starting with "WHY?"

The really lethal things could be allowed only in designated areas under the control of a gun club which in turn is closely monitored. Then those poor individuals who can only get hard after firing a mini-gun have hope.

In muggings, pepper spray / chilli spray or a tazer works, and ensures that some panicked accountant doesn't drill someone 50 metres away because their aim is so poor that they missed the person approaching asking for directions. That the person who is to be mugged draws a weapon faster than the mugger either means they are supernaturally fast or isn't a factor that should be looked at too closely (I assume everyone walks around with a loaded pistol in their hands - just in case.