Reb and USAF:

Promise me, both of you, that when you eventually get promoted to some high rank, you'll do away with gun buybacks in your respective jurisdictions.

No gangbanger is ever going to give up their firearm for $50 gift cards to the grocery store.

Promise me!!!!!

Depends. Would I get to cherry pick toys out of the return bin?

Gang-bangers aren't going to turn their guns in, but people who do are less likely to sell them to bangers, or have their kids do the same. It provides a way for people who don't want their guns to get rid of them in what seems like a safe and legal way. When someone who inherits a gun and has no idea about laws and value, they have a known and trusted way of getting rid of them rather than shady pawnshop owners. I still think police forces should be able to cherry-pick through them, and auction them off to buy body armor and other kit items. 

Awesome, we have another one of those 'learning' bots.

As I mentioned, in places like NYC, the city doesn't want to get into the 'business of selling guns' to people, so the weapons secured in the buy-backs are meticulously cataloged and destroyed. My father in law has seen everything from pure junk to honest to god collectors pieces be turned in for those gift cards, and every last one of them destroyed because of the city's proclivities on firearms.
You could surrender a one-of-a-kind piece, hell, it could be a presentation piece that was given to George Patton by the ghost of George Washington....and it would be tossed in a bin and demolished with a barely serviceable sears and roebuck single shot .22