I have seen a couple of post WW-I Fox doubles that were roll stamped on the tops of the barrels Chromox but you could still see the Krupp markings on the underside of the tubes. Unfortunately I've never purchased such a gun. After WW-I lots of folks didn't want those Heinie barrels on their gun. I can't fathom any reason a set of Lefever barrels should be marked Krupp on the exterior and the underside and also carry the LLH. Very perplexing!!!
The tube-makers -- Krupp, Whitworth, L.Lochet-Habran, Didiere, etc. -- sold rough tubes to the American double gun manufacturers who then made them into barrels. The imported rough tubes came in at a much lower tariff then a finished product. Sanderson Bros. & Co. set up in Syracuse to make tubes here.
