Nice. A book with a prize inside.
The gun is a .31-caliber, black powder pistol that was apparently made by Italian gun manufacturer Armi San Marco, which reportedly made replica period firearms in the second half of the 20th century.
This is a dumb story. The book was not a real book, but a book safe. The gun was a replica that probably does not work. The likelyhood of finding the owner is nil. The “book” came from a central depository here in Maine of all of the Goodwill stores.
Good pr for Goodwill. They should sell the gun, but probably won’t.