In my experience RL-15 is the most temperature-resistant of the Reloder powders, and it was improved considerably in the late 1990's. But it still isn't as temp-resistant as the Hodgdon Extremes.
It is, however, one of the very best all-around powders for the 9.3x62. I've gotten excellent results with it with bullets from 232 to 300 grains.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
