Ned Schwing's book on the Model 21 and his discussion of the steel used in Model 21 frame manufacturing has nothing to do with Fox shotguns. The Chromox and Krupp steels referred to in Fox manufacturing were for the barrels and not the frame. Winchester specifciations for the Model 21 and Fox specifications have nothing to do with each other.
Fox recievers continued to be of mild steel and required case hardening while Winchster recievers were manufactured of high tensile steel requiring no surface (case) hardening which resulted in Winchester recievers being blued and Fox case hardened.
Dick
You are correct Dick.
I also suspect the "chromox" barrel steel wasn't used for frames.
You are also correct Chuck.
Dick lays it out quite
matter-of-factly and is entirely correct.
ALL of the Fox frames were cyanide cased (after about 1910 or so) and were cased by Fred Heinzelman & Sons in Carlstadt, N.J. for as long as Fox was in business.......Heinzelman & Sons is still in business today and is still doing guns (110 years or so) and could probably answer all your Fox receiver frame alloy questions for the data compilers here who are interested.
Cheers,
