Is there any appreciable difference between the Field and Ideal grades of late 30's / early 40's LC Smith doubles?
Engraving, looks, if that means anything to you.
There is a functional difference between Smith guns made before 1939 and those made after 1939. In 1939 L.C. Smith went to the "improved stock design" which was stronger than the earlier stocks. They also built a taller profile solid rib dubbed the "Single Sighting Plane Rib" (the double that sights like a single). In hand, these later guns felt like a single barrel repeater and, depending on barrel length and choke, pointed and performed very well.