2-piper I do not dispute your points. You have most likely forgotten more about this than I have learned. But if the goal is to color alone is that not done at the lower temp.? Hardness is already inherent in the metal. The color is all that is needed with 4140. Other milder, softer metal could be hardened by longer time exposure at a higher temp. for what I understand from my notes. I doubt H&R used only 4140 steel in making all those single shot guns. I suspect they used an easier to work metal and then hardened it with a case color change as a minor side effect.
