The very first 9.3x62 I loaded for was purchased for a friend from a local store. Before sending it to him I loaded for it just to see what would happen, trying IMR4895 and H4350 with 286's., which were recommended by many people back when the 9.3x62 was rare in the U.S. Neither worked all that great; H4350 was too slow and IMR4895 too fast.
I bought my own 9.3x62 a decade ago and tried Big Game right away with 286's, since it was right between IMR4895 and H350 in burning rate. It shot so well, both in terms of velocity and accuracy, that I've never fooled with anything else since.
Based on my experience with Varget and RL-15 and 250's, however, I'd say that around 57-58 grains of Varget would be about max, and 58-59 grains of RL-15. However, I must also note that Varget doesn't seem to vary much between lots, but I've seen RL-15 vary as much as two grains in cases the size of the 9.3x62.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
