[edgarspencer]

Ed, I couldn't speak to any particular range of normalizing, tempering or annealing of receivers of any particular period of manufacture. Speaking in more general terms though, any particular heat treatment is a function of the base metal chemistry. Given that a heat treat shop knows the chemistry, very little in times and temps has changed.
Most all quality firearm receivers are milled from forged steel blanks. These forgings, prior to mechanical process to achieve their near-net shape, were born from molten metal, a media I am intimately familiar. For my last 25 years of my working career, I owned and ran a pretty sophisticated steel foundry. When I was a youngster, the company operated a "wet" analytical laboratory, for material analysis. The drawback of the "old process" was that you were performing an analysis that took hours, and well after the furnace had poured to the 4000-15,000 pound ladles, and the castings were poured, and cooling.
It was only by past proven 'recipes' and known chemistries of raw materials, that specs were met, or, within the range of the given PO specifications (ASTM, ASME, ANSI or Mil-S-xxxxx) As growth permitted, the company changed to Spectrometer analysis, both x-ray flourescent and vacuum/optical emission. This allowed the melting department to know exactly what to add (or boil off with liquid oxygen) to hit an exact chemistry.
This information was what the heat treat department needed to know precisely what times, temps and quench/cool down methods were necessary.
Even the old gun-makers had the tools (chemistry of the forged blanks) because the steel mills supplied chemistry since early steel makiing started. What made it more difficult was the lack of consistency through time. it was essential the heat treatment departments knew exactly, the tracability of the given blanks to the analysies supplied. Traceability is the major function of QC departments everywhere.
As an aside, Ruger, in Newport, up your way, is one of the only present day gunmakers who produces all their receivers from (investment) castings, not forgings.
Mike, That old SS frame cold still be saved. The HIP process, not one which many but specialty firms perform, is the Hot Isostatic Press process, where casings and forgings are put under, are you ready(?) up to a half million PSI. Apart from the obvious compression, grain structures of incredible fineness are achieved. I don't know how badly it was stretched, but good cut/TIG weld procedures can do alot. Also the hardness could be tested in a nearly non destructive way using either Rockwell, or micro-braille hardness testers.
FWIW, I don't agree that the "best" coarse is to not re-case. It has to be determined on a gun by gun decision. If the end result is a near-new restoration, the value (sentimental or monetary) of the end result has to justify the expense invested, and you don't go to the corner store for prime rib when the best butcher is just down the road.
Jeez, I miss my job.