I'm sure that the makers would have provided more detail as to what their actions may have represented had they ever thought that we'd have so many questions decades after the fact; but they didn't and that's why we have so much fun "theorizing". Again, I have no answers as to the unusual engraving of this Trap Grade; perhaps the "3" stamp was a signal to the engraving shop as to the engraving style the customer had ordered? Grade 3 engraving patterns were still available when this gun was built as we see from the 1941 Kraus prepared engraving schedule below. The dollar amounts quoted represented the engraving shop cost; I've no idea what the company may have charged the company. But note that the cost to engrave a Grade 3 gun (all but barrels) was $3.80 in 1941; and that cost is the exact same cost for engraving a Trap Grade gun (barrel engraving was $.20 extra). Based on that information, the original customer may have had to pay zero extra dollars for the Grade 3 engraving he preferred?
Again, it'd be nice if we had the answers to many of our questions; the photo below the schedule being another. Can anyone explain why the gun in that photo is factory Graded 3E?