I sold or traded off all that stuff at a gun show in Virginia.
Given that this is NYC we're speaking of, I'm not so sure that would work.
Officer: "Sir, our records show that you have 12 firearms that have retroactively been made illegal to possess. I'm here to confiscate them."
NYC Gun owner: (smugly) "I lost them in a boating accident 5 years ago"
Officer: "That being the case, you do have records showing that you reported the loss of these registered firearms to the proper authorities shortly after this 'accident', do you not?"
Gun owner: "I...er...uh..."
Officer: (getting out his cuffs) "You have the right to remain silent. Any thing you say..."