The store has to keep records on who they sold it to. The FBI / ATF can track it to a store and the store has to keep sales records. Thats so if they find your rifle stuffed up a dems ass and repeatedly fired they know how to get in touch with ya and ask ya iffen ya knows wheree your gun is. Not the most efficient procedure, but it's what they do.
...down here in toadsuck we generally know who a gun belongs to by the number of notches carved in the butt.
Liberals are like a "Slinky". Totally useless, but somehow ya can't help but smile when you see one tumble down a flight of stairs!