Again Andy, Canada tried that game, and abolished it, a "National Gun Control Registry" for all guns, including long guns,rifles, 22s shotguns. It was an expensive nightmare that was an utter failure.
I will say this again Criminals do not register, buy lawful weapons, whackos steal weapons, they will kill and will get what they need to accomplish there sick goals.
I don't pretend to know the answer, but do know criminals, psychos, murderers do not concern themselves with lawful gun ownership, they get what they need, whether lawful or illegal, to get a means to their end. No registry, buying rules, safe responsible ownership, would curb a blood thirsty killers obsession to shoot and kill innocent people, they just do it..