American citizens do it 1,000's of times a day, one would think if it was a problem you would constantly hear about good citizens being arrested and charged with Federal Crimes. But yet we don't.I'm aware of that one. It pertains to "for his or her own use". It's not "to another person". In the original scenario above, Person A is mailing it back to Person B. A temporary transfer (probably unlawfully per federal law) unintentionally took place when the firearm was left. To get it back to Person B who resided in another state, it would have to be shipped to an FFL in Person B's state.