Can you account for every gun you have ever purchased that you don't have any more?
You gotta be kidding. After 500 or so, a couple of burglaries, 45 YEARS of gun ownership and a continuing turnover so that the total at any one time runs around 50 or so? The ATF doesn't keep records that good. Literally.
Of course, MOST were antiques, so little threat out in the world there. However there was that one idiot in Houston who, after the burglary, thought that those .44 mag cartridges he had fit real nice in the 1870's Adams revolver. Tried to hold up a 7-11 and blew his hand off (well, mostly). Police tried to give me back the pieces. After all, it was the only .455 Adams ever stolen (and later used in a crime) in Houston's known history.