I use Hornady New Dimension Dies for 9.3x57. The expander die is designed to neck up easily. I use Norma brass for this caliber. It is not cheap at about $1.00 per case. But it lasts a long time. I have not formed any 9.3 from 8mm as I really don't need to. It is not a caliber that you take out and shoot 200 rounds in a day. 232gr bullets suck. I have not tried 250gr. 270grJSP, 285grGCCL and 286gr Partitions all shoot great. W/ IMR4064 it has very mild recoil, even at max loads.
Freedom is not free. The best of us always leave too soon.