I am also aware of the data base gun manufacturers have. But firearms down thru the years have been sold, exchanged, passed on after death and gave away as gifts. There could be literally tens of millions which fit that category.
I do not think appeal of the Second Amendment is going to happen. But when you have a retired sitting Justice who feels it should be, then it is not impossible. And I am mainly speaking of legislation which can be interpreted by the Supreme Court to be Constitutional. The Heller case for one, was a 5-4 decision which was a landmark decision outlining the Constitutional right to use firearms for self defense as a right apart from a militia. If that had gone the other way, the states would have much more power to control the citizen's use of firearms.