We should also remember that back when L.C. Smith, Parker and Ithaca (among others) started, 1020 mild steel with lower carbon content was the "state of the art" for forging receivers on drop board molds-- and "double fitting" was std. for gun making then- not until WRA, a pioneer in metallurgy working with USSteel, developed the M21 and the fitting of heat treated AISI 4140 nickel chrome moly alloyed medium carbon steels- as heat treated, eliminating a costly and somewhat in-accurate surface hardening technique- Dr. Gaddy was a very well informed man, and his detailed analysis and printed results are 'gospel"--
