Just like a scene out of "Antiques Roadshow," a woman in Hartford, Conn., turned in an old rifle to her local police station's gun buy-back, only to discover the gun was worth anywhere from $20,000 to $25,000. The woman, who wishes to remain anonymous, inherited the gun from her father who had brought it home with him from Europe as a memento from World War II. The two officers conducting the gun buy-back, who are resident gun experts for the Hartford Police Department, informed the owner she was in possession of a Nazi Assault Rifle, the first of its kind,...