Well from Blasers site it appears your "big" choices for the R93 are 9.3x62,9.3x64, .375H&H and .416Rem
Having owned and used all 4 calibres.

At 50 to 75 yds don't see much difference in the dying, stretch that to 200 , the X64 and the H&H still seem pretty equivalent, with the X62 and the .416 dropping off.(Again, this is with good shot placement.

With "poor" shot placement the .416 (@ short yardage) seems to have a slight added "pop" with its 5000+ ft/lbs.and larger frontal area even though the energy of the X64 and H&H are right up there.

FWIW ,If I were truly "alone" out there, I'd carry get a DR,5000ft/lbs and up,and I own two Blasers.

Sure, you can kill with a 7 Mauser or a 6.5X54 Mannlicher, its been proven, but it has been proven just as much, you can't reliably STOP with one.

Bigger= Better , generally, in stopping.