Want to have some reasonable gun control?
Expand the NFA to cover all repeating firearms. Provide a final date that no previously-unregistered arms can be registered after. Grandfather all existing repeating arms under the $200 tax stamp (each) and then adjust that tax stamp price for inflation, from 1934 until today, for any future transfer ($4300). This doesn't violate the 2A according to any existing SCOTUS opinion.