I've noticed some differences in NID Grade 4E engraving. My 1941 vintage 16-gauge has less
than my 1936 12-gauge and 1933 20-gauge.
Also, in his book, Walter shows pictures on page 85 of a 4E with an oval with a bird on the bottom of the frame, which is much nicer than the floral work on mine, and as was pictured in the catalogues from 1926 to 34.
You'll notice in the catalogue cut the wedge of floral engraving flows back from the forearm iron while on my 1941 gun it flows foreward from the trigger plate.
