I have serious doubts that case-hardening gives much of a spring effec to a piece of steel. After the case-hardening process if there was warpage etc, these gns were "HardFit". This meant they were bent back into shape. I do not believe that in this hard fitting they were moved enough they would not have gone back had they had a spring temper, but they stayed bent, indicating they were not of the nature of a spring.
Case hardening affects maybe a surface depth in mild (AISI 1018) forged parts like receivers of 0.0025"- annealing affects the entire area, but remember, whenever you subject a formed metal part to heat input, it flows towards the thinner sections- all the great American made side-by-sides (except the Winchester M21) were "double fitted"-- first in the pre-case hardening state (soft fitted) and then final or hard fitting after case hardening-- The great Parker authority now the late Edward Muderlak discloses this quite well in his book on Parkers, and even shows fotos of the late Dr. Oscar Gaddy with his furnace and chill box-
I have seen how well fitted the AH Fox guns are from my Sterlingworths- I would agree with the other gent who posted here- I would have the gun re-case hardened by someone who really knows what they are doing--
