gun control
My simple thoughts:
All firearms must be registered with a central, national registry.
Registration for guns you currently own is free. Registration for guns purchased in the future is a nominal fee to cover processing. Each gun has exactly one owner.
You can personally possess any gun which you own. If you don't own a gun, you must be in the presence of the owner in order to possess it. (e.g. you can lend your gun to a friend who's going hunting/at the range with you.)