I noticed under various topics the discussion of annealing and case hardening. Having been a toolmaker and involved with heat treating for 30+ years I don't see how you can apply any amount of heat to an action or critical part without knowing what the material you are working with such as 1010, 1018, 8620 etc. When case hardening different materials require different temperatures to acquire the proper case depth and core hardness. It sounds to me like this is an accident waiting to happen.

Without destructive testing, I doubt anyone could tell you the metallurgy of a Hi Wall, Rolling Block, or Ballard of the 1800's. I also seriously doubt if any two of the same model were exactly the same metallurgy either!
Basically, there wasn't anything such as metallurgy in the 1800's, as it is today.
Processes used to heat treat or case harden firearms in the 1800's were basically seat of the pants engineering, and repetition of procedures that worked most often.

Disclaimer:  Everything I know about about heat treating is second hand, but since fools rush in where angels fear to tread, here goes;

1)  From all indications, most of the heat treating of years past seems to be more properly a type of surface treating.  I know of several reports where the metal seemed almost fluid underneath in comparison to the cased surface.

2)  Even within the same receiver (or other part) alloys during the "Golden Age" were  not all that consistent.  Witness the discussion on this board a few months ago about whixker-like carbon inclusions popping up as high-wall receivers were polished.

Ziggy, I think you are raising a valid point from a purely scientific and theoretical standpoint, but from the applications in this venue, it may not be a practical concern.  The big thing that seems necessary is to use some means of preventing warpage of parts being surface hardened.  JMHO-YMMV

Froggie

Some years back a writer did an article on Winchester M1885's to see 
"What They Were Made Of?" he got bits and pieces from contributers from many different actions that covered nearly the whole range of manufacturing . The material was submitted to a materials lab for analysis using the then Spectrometer system that was the state of art at the time, The results suprised him. It turned out that the metallurgy was very consistant. The Lab report stated that the material was so consistant and the Chemistry looked to have been specifically created to aid in Machining processes. In Campbells book he has a chapter on Steel suppliers to Winchester and traces the evolution of barrel steels from Mild steel to the early versions of Nickle Steel barrels which by the way was being used some number of years before Winchester announced it and started marking barrels as Nickle Steel.  When Winchester in the early  1900's changed the heat treat specification for recievers it became the Factory standard and if you sent a Rifle in for rebarreling or change and it was case hardened it came back re-heat treated and stamped with the V P proof. a freind of mine submitted a case hardened double set action to be rebarreled to .22 Hornet and was furious when they handed him a Blued action rifle a few weeks later. The Supervisor explained that this was the standard specification at that time and if he had insisted on keeping it case colored they would have been forced to refuse the job. As another example consider how many Winder Muskets have been rebarreled to modern high pressure calibers. .219 Zipper, .219 imp Zipper, .219 Donaldson Wasp and .222 Rimmed and many other rimmed wildcats such as .25 Niedner Krag. Now I know from experience these Winder recievers are Butter soft. They machine easily. The real strength in Hiwalls and Sharps Borchardt and Remington Hepburn actions is the Robust strength of the action design, Compare the surface area of these breech blocks in support to that of most Bolt Rifles and you will be suprised.
Well enough of my ranting. Regards, FITZ.