FWIW, your gun was made by Savage rather that Fox. Don't know if that makes any difference; maybe, maybe not. As a side note, I have a 20 ga Sterlingworth, SN261xxx. According to the factory letter, it was completed by Savage and shipped from Utica on 10/22/1930 but all markings are Philadelphia. I suspect the parts were made in Philadelphia and shipped (unassembled) to Utica soon after Savage bought Fox. I never had a FTF but I haven't fired the gun in years so it never digested any of today's "modern crummy ammunition."
