Back in the early 80s. I had an FFL selling to Marines I knew. One morning @0600 got the call from the Fibs about a Colt Python I had sold. 5 #s in the serial number but only the first number remained clear. The recovered gun had been used in an armed robbery less than 24 hours prior.
Ah. The form tells them who purchased originally and from there it is a crap shoot.