FRAMES
No way around the "not the best" steel Hunter Arms was using, likely sourced from Sanderson Bros.
c. 1890 Hunter Arms Fulton Transition L.C. Smith Hammerless and 1909 L.C. Smith No. 00
Both were non-standard but similar to Bessemer Resulphurized (very high Sulphur) AISI 1109 Low (.09 & .12%) Carbon Steel.
The industrial standard tensile strength for non-heat treated 1109 is
56,000 psi
Plans & Specifications of the L.C. Smith Shotgun by William S. Brophy contains an undated but likely
post-1913 Materials Specification chart indicating AISI 1020 Carbon Steel for the frame.
c. 1900 Remington Hammerless Model of 1900 -
Bessemer Rephosphorized Resulphurized AISI 1211 Low Alloy Low (.08%) Carbon Steel
The industrial standard tensile strength for non-heat treated 1211 is 75,000 psi
c. 1892 New Ithaca (Hammer) Gun -
AISI 1015 Carbon Steel
c. 1927 Crescent Empire No. 60 -
Non-standard AISI 1015 Carbon Steel with low concentrations of Nickel (.05%) and Chromium (.08%)