I think the current laws are fine as far as ownership goes - in my state anyway.
California and so forth really need to lighten up if you ask me, but I don't get a say in that.

Now justice for misuse, needs to be swifter and more decisive. As in a fast track to a dirt nap.

For example:
If I wanted to detonate grenades out in the boonies somewhere (where property damage didn't apply either) I'd have to get a class III license, which is an ordeal, but can be done. Then it would be my business and those that didn't like it could pack sand for all I care.

However, if I where to use them in a criminal or reckless manner then I should be severely dealt with post haste.