This is an old hoax, really.
The idea would be a non-starter, anyway, the kind that "keeps honest people honest".
Besides, for those of us upstanding citizens, who filled out proper paperwork when they bought
almost all of their guns, they already have a better system.
Remember when the "Census walkers" were prowling the neighborhoods storing addresses, and GPS co-ordinates?
Now think a minute... not too hard, now...
What didja come up with? Hmmmmmm?
Did it look anything like a map of the neighborhood, including:
- Street address,
- Resident's name,
- Number of registered guns,
- Location of doors,
- etc?
Smile!! 
You've just been "data-mined".
Fred