Difference being it was lost....not stolen.
Kinda gray on that point. It was accidentally left behind, not abandoned in the true sense, and Buckingham returned shortly after to retrieve it and then made a well-publicized effort to recover it. I don't know how finders/keepers laws work exactly, but it would be hard to argue that he abandoned the gun for someone else to take possession of.
On the other hand when Bo-Whoop did resurface, did anyone contend that it was stolen property? I wonder if the statute of limitations had run at that point.
The general common law rule on lost property - finders keepers, if you will - is that the finder of lost property has good title to it against the whole world, except for the true owner (who lost it). As to abandoned property, good title goes to whomever picks it up.
The difference between "lost" and "abandoned" is not subject to a bright-line test but rather depends on how much of an effort and what kind of effort the original true owner made upon realizing it was missing. In the case of Bo-Whoop, putting ads in the paper and otherwise publicizing the loss moved it strongly in the direction of "lost" rather than "abandoned".
In theory, there is no statute of limitations on recovering lost or stolen property and returning it to the true owner. Just ask all those families of Jewish victims of the Nazis still following up on and recovering artwork taken from their ancestors 70 plus years ago. Of course, the person who held it during the interim is often deemed by the court to be entitled to something for their trouble in preserving and maintaining the property and that might wind up being more than the property is worth. And, the longer the time between loss and recovery, the harder it is to prove the underlying loss was wrongful.
Finally, as to intermediary purchasers, the guy who winds up having to give up the property - so long as he was a bona fide (pure heart, no knowledge of wrongdoing) purchaser for value - gets to look to the guy who sold it to him, to return his money. This goes up the chain to whomever it was first sold their found property.
Many states have statutes on found property and the related topics, and the law does vary widely. What I've stated are the general principles taught in the first-year property class in law school.
