Stacyhs
Penultimate Amazing
I guess the question becomes: What do you want the registry to do. (Which of course affects the question: What do you want the registry to be.)
Do you want to handle all potential situations (such as: situations where guns are stolen from a home but not used in a crime, or something that can warn cops if a domestic dispute they are responding to might have firearms present? ) Or do you want to just concentrate on "street crime"?
If your only goal is something to handle your regular corner store robbery, then a smaller gun registry (only dealing with new gun sales) would be appropriate. If you want something more comprehensive, then you need to figure out how to handle older guns that have been sitting in someone's closet for year. Then, once you figure out what type of registry you want (comprehensive vs. new gun only), you have to figure out how much value it will provide (and how much money is worth investing in it.) How will it help solve crimes/prevent gun violence, and are there alternative ways to spend the money that will be more effective.
Someone posted a reference to the Canadian gun registry earlier, which turned out to be a big failure.. Canada has been registering handguns for decades, but at one point the government decided to also register rifles/shotguns (including older ones). It was originally supposed to cost ~$2 million to set up, but by the end it had cost over $1 billion. And it STILL wasn't comprehensive (since many people either didn't register their guns, or tried but the government messed up the paperwork).
Even if those guns didn't work, or were old enough to be considered antiques, there are plenty of guns that are slightlyl newer (decades instead of centuries) that would still be functional and even used on a regular basis.
I can't give you a detailed answer to a question like yours because, frankly, I don't know enough about gun registries, etc. I know the limit of my knowledge and don't want to just pull things out of my arse. I can only say that guns need to be registered regardless of who sells/trades/buys them, whether new or resold, as long as they are usable.