I know a guy who has a genuine GI 1911 that was his father's, and I know the story about how it was obtained. "Legal" isn't really a definition one could use - IIRC, it was more of a situation that arose from the days of paper records, and this pistol falling through the cracks somehow with no official paper record. According to the unit, it simply didn't exist.Don’t know, never got the story
There's a fair amount of stuff in my Guard unit's supply area from years gone by that have no records - either they were obtained through less than honest methods and therefore no paperwork every existed on them, or the paperwork got lost over the years - most of these things are literally decades old. (Not weapons, but other mission related gear.)