Ive been doing CCH in the shop for the past 15-20 years, and Ive been researching it for longer than that. Keep in mind that case hardening via bone char has been around for a loooong time, and was actually a commercial hardening process; everything from locomotive parts to delicate measuring instruments look at Starrets early squares (beautiful Colors), Ive got mid 1920s tap wrenches with gorgeous CCH. Pre WWII bone charr case hardening was well known and well established.
With that said, I dont think anyone will get original colors, for a variety of reasons, although I can get very close to Winchesters colors. OBTW, I do have Winchesters CCH formulas notice its plural, meaning they had different processes/formulas for different parts.
Here are some of your challenges:
Case hardening/Quench temps: Back in the day they did true case hardening, meaning the parts were quenched at 1600 degrees +. At those temps the metal will move. Winchester experienced a high warpage/cracking rate, and in 1903 stopped CHH. A large company like Winchester or Marlin can absorb a certain failure rate Can you?
Virgin Steel: Ive had the steel analyzed, its a very low carbon steel. Each time the steel is case hardened, carbon is added to the steel. The more carbon in the steel, the higher the chances of the steel warping/cracking.
Wood/Bone ratio: Different ratios will produce different colors/look.
Bone Char: I suspect pre-1900 the bone char was buffalo, today its most likely sheep imported from Scotland.
Water temperature: Water temps have a significant impact on colors, I suspect they used well water. Ground water temps vary across the country, water temperature is 2 to 3F above the annual mean temperature of the locality, because of this, well water in Mass is significantly colder than well water in Florida.
Shall I go on?
