Tanky: I have 5 frame analyses at the bottom here
https://docs.google.com/document/d/1dnRLZgcuHfx7uFOHvHCUGnGFiLiset-DTTEK8OtPYVA/edit

July 1, 1920 "American Machinist" published an Ordnance Salvage Board Surplus Property Sale of almost 75,000 pounds of “Spec. Shape Gun Steel” from the A.H. Fox Gun Co. with C .15-.25%, Mn .5-.7%, S & P < .06% = AISI 1020
https://books.google.com/books?id=ezRMAQAAIAAJ&pg=RA1-PA409&lpg