Greg - Perhaps you misunderstood my post. I did not say ALL modern powders carried that trait. The Winchester powders, designed way back in the 50's and the hodgdon ball powders are not the same as the ADI or Hodgdon Extreme powders in temp swings. As far as I know, even the AA balls powders have to be carefully loaded in hot temps.

The modern 'Reloader' powders are supposedly better than any of the spherical powders for stability in temp extremes - but, they don't match H4895 or Varget, which are both good powders for the Taylor - which can safely be loaded to 60,000 - 63,000 PSI in the winter and fired in 120F temps in the summer.

Today, with, OK - some of the modern powders, pressure excursions with temperature are a thing of the past.

Temp excursions were the reason the Notro Express rounds weer loaded to such low pressures - put another way - temperature extremes with the powders available way back THEN, are the reason the Nitro Express cases are so large for their ballistics. The cases had to be that large to get the performance desired as pressures safe to shoot in Africa.

H$ll, even 1950 to 1960 era IMR4320 loads for 400gr. @ 2,350fps to 2,400fps were safe in Africa, in the .416 Taylor. Today, we have much more stable powders than that, and performance can be improved upon even more. Amazing what a bit of technology can do. Smaller rounds today outpace the larger rounds of yesterday.