Dew, in response to your question whether the barrels of my 1901 10-gauge have an 'H' stamped on them, they have both an 'H' and a 'D' separately stamped on the tubes.
I have awaiting reconditioning a 1912 12-gauge Model F with standard 2-rod Damascus barrels. This gun matches the catalog description of the $25 New Model F gun. It has HRF stamped on the tubes.