My first loads with my 9,3x74R were with IMR 3031 and 270 Speer bullets. While I never had any high pressure problems these are the only loads that the bbls cross fired.
I later found that RL-15 gives excellent accuracy with the 270 Speers, and I use 65gr of IMR 4831 with the 285/286 bullets. 286 Woodleigh Solids seem to shoot best with 63.5 gr of IMR 4831. I say seems to as I do not declare a load good until I have several different firing sessions with it.