I did a search and I can't find much information about the effects of mirage and the effect of temperature on the burning rate of powders. I have Exbal on a pocket PC so most environmental variables are something I can correct for. Just out of curiosity, do you guys chrono your loads at various temperatures? It seems to me plugging in the air temp in Exbal is dandy, but are air density changes due to temp as important as changes in burning rate. I am also curious how you guys correct for mirage? I hunt a lot of varmints in hot dry weather and I know the effects of mirage can be substantial. The same can be true in the winter when it's bitter cold. What's the secret?