Note that 1250-1300°F will affect the case. It will draw (temper) out virtually all the hardness put there by the quench. I had started a discussion privatly with Oscar, but unfortunately didn't have opportunity to complete. Oscar's technique was I think to heat part high enough for absorption of a little more carbon, then drop the temp to below the critical for the low carbon core, but still above that of the high carbon case for quench. This gave max hardness for the case but preserved full softness to the core.
The L C Smith "Parts & Specifications" book lists their frame for at least some part of it's life as being from 1020 steel. I think this is probably fairly typical for the period.
From all I am able to gather from the past, this procedure "Was" done for the "Hardness", color was a by-product, though they soon did work to develope the colors to their best, while retaining the hard case.
