I worked w/a gunsmith that insisted the correct term was 'draw TO temper' and he corrected me every time I said 'draw the temper'.
Of course, I purposely from that point on said 'draw the temper' just because.

Whatever,,make it dead soft, make it glass hard and then draw it back to spring hard.
Works for me.

What about that infrared thermometer,,any better, more accurate than a regular thermometer?
I've gotten along with stick thermometer in a lead or niter pot. Or just judging by eye w/a torch heating the spring from below on a steel plate.