You are correct about the owl on the grips. All third model IJs have the owl's head looking out, as opposed to looking forward toward the barrel on earlier models. I searched Bill Goforth's book for the wording of the patent dates you quote and cannot find an exact match. Is it possible the markings on the bottom of the butt strap are so faint that you misread them? Also, serial numbers on model three hammerless guns should be 5 digits, not four, preceded by a letter of D or N. All this info comes from Goforth's book, pages 48 and 49.