2. Handguns must always be stored locked, and the unlocking mechanism must be stored separately.
3. The registered owner of a handgun is responsible for any deaths or injuries that are caused by that gun.
4. There will be some reasonable mechanism for reporting the theft or destruction of a registered handgun.
5. If a gun that is registered to you is ever found unlocked, or in someone else's possession, there will be hell to pay.
6. If you're ever caught with an unregistered gun, there will be hell to pay.
Justification: I want handgun owners to be responsible for what is done with their weapons, and for them to have a really strong motivation to keep them safe.
I'm sure there are holes in my proposal, as it's more conceptual than complete.