I am glad the Authorities were not tough on you over the markings on that old gun. The only place I have ever seen a large italic serial number was on an Argentine contract or Systema.
I do have one sidebar: Tom says "I have a Remington Rand slide on an Essex frame. The serial numbers don't match, but the one that matters is the one Essex put on it when they made the frame."
The numbers don't match WHAT? At one time Colt slides were numbered to their frames but only 1937-1943, not before or after. I never saw or heard of a Remington Rand slide with serial number. We don't have DWM putting a number on every part big enough to hit with a stamp.