Controlling violence is one of the primary justifications for government. You're comparing apples and oranges - Violent acts and prohibition of inanimate objects don't fit in the same scope.
Prohibition of alcohol would be a more apt comparison.
Prohibition of alcohol would be a more apt comparison.
Cars physically hurt people even when they aren't hitting people.
I think your rule about possession being different from action doesn't hold water at all.
If you're an ultra-libertarian I think you need to get your externality philosophy straightened out first in your model of utopia.