Guys,
I’m revising the hotplate mould temperature I posted earlier. Due to a response from an experienced caster that monitors his mould temp, I just checked the calibration of my digital thermometer setup. Apparently the thermocouple probe I was using is bad. After switching to another probe and checking the calibration, the correct hotplate mould temp is around 465 degrees F. Interesting, it’s been my experience that when a thermocouple fails it typically reads less than the actual temp rather than more.
My technique was to over-heat the mould then cast until the bullets lost their frosty appearance, at which point the mould temp was measured by inserting the probe into the bullet cavity. From experience I know that as soon as the bullets lose their frosty appearance the weight is within +/- 0.5gr of their average weight.
See the photo below for my initial setup. You'll note the digital thermometer reads 465.0 degrees and the PID in the background reads the casting alloy temp of 766 degrees (1 degree over the setting of 765 degrees).
Wayne