Definatly use the 286 gr. bullets at the slower velocities of most 9.3s...

The 320s do not work particularly well unless you can step up the MV on them...I shoot them at near 2400 FPS in my rather long throated 9.3x62 with a 26" tube and a warm handload and they work well, but did not do well at all in my 20" barrel at about 2100..