I recently weigh sorted a batch of bullets (Lee 225-55) that I'd run. It's been some thirty years since I weigh sorted anything throwing out the 30 or so at the extreme edges of the run, the bullets dropped with a max spread of .8 grains with right at half of the run falling within .2 grains.
My question is this, what effect if any does all the heat control you're putting into your casting having on your end product? Has it reduced the weight spread of your runs?