I've always wondered if the police could use that to track down the original owner by hitting up all the local gun shops until they get a match. It sounds arduous, but possible, and would only tell the original owner, not the one who necessarily committed the crime.
If the police recover a gun used in a crime, they can contact the manufacturer and the manufacturer will tell them what dealer they shipped that gun to when it was first sold and when it was shipped.
The PD then contacts that dealer and asks the dealer to look up his records from that year, located that sale sale, and give them the name of the original owner.
Then they contact the original owner.
Often the original buyer has moved out of the state and is no longer able to be located at all.
However, if he or she is still around, that owner may be able to tell them that they sold that gun to another dealer, in which case the PD then goes to that dealer and continues the search.
Or the owner says, "I sold it via a legal private-party sale and I do/don't remember the buyer's name." There, the trail usually goes cold.
And the older the gun gets, the more likely it is to have passed through several hands -- and it only takes one face-to-face sale, trade, gifting, etc., for the trail to be irretrievably broken.
But even ignoring private sales, if you buy a gun and later sell it to some other dealer, there is no link-up between those two bits of information in two different dealers' bound books and file cabinets -- except for information in your head regarding that connection. No master database somehow connects all those dots.
So you can believe that the odds of a gun being "traceable" are pretty slim.
(Yes, some states do have registration and databases. But federally, no.)
