I have owned and looked over a few D M Lefever'S over the years and most had the grade stamp under the grip cap (capped PG original stocks). I have not looked for the grade stamp under the trigger guard tang on a straight grip gun, but they might be stamped there. I once saw a grade 5B 16 gauge with left hand top lever (pivots clockwise) that Tom Gibbons had a show in the mid 90's. Very rare and beautifully engraved gun but he wanted more for it than I had in my retirement fund!