Hard to ascertain the finer points. Savage calls it retempering. I don't think there is any info on what they did prior to that. Was there a lesser degree of heat treatment on older guns?
When heat treating steel, the part is ALWAYS brought to full hardness first. Some call it "glass hard". This is accomplished by raising the temperature above the "critical" point, which varies dependent on the alloy.
It is then allowed to cool, then tempered. Some manufacturers call it "drawn down". This is done at a much lower temperature, dependent on the alloy and the desired hardness. Depending on the alloy and it's intended use, it may be "re-tempered".
In the time frame being discussed, the steel industry was still learning a LOT of details. Remember the early Springfield 1903's?
Today we even have cryogenic "heat" treatment which is a whole 'nuther can-o-worms...
