sweat spot is in the eye ( or in the shoulder) of the shooter,
The 375 Ruger case has more volume, so for bullets with similar SD (210 gr in 338 vs 250 gr in 366 and 250gr in 338 and 286 gr in 366) the 9.3-375 takes 8-10 gr more powder ( I use H4350 and H100v in the 9.3 CAN.
Not sure how much velocity difference that would generate, I have not pressure tested my loads and stayed on the conservative side. but about 2900 fps for a 250 gr should be within limits, possibly 2950 . And the 338 gets 2700fps with a 250gr, so necked up a 250 gr bullet from that case could be a bit faster . A bit like the 280 REM vs the 30.06 where the difference in a 175 gr bullet makes barely 100-150 fps.
Hunting wise we'd probably be splitting hairs.
Just wanted to leave the note that a 9.3 from a 375 Ruger is an easy and well behaved wildcat, I think, if standardized it would be a tough competition for the favour of few remaining 9.3x64s fanatics out there.
