I've been making some observations on the original 9.3x62 chamber dimensions. This would be our 1922 Waffenfabrik Mauser Oberndorf Type B sporter:

The throat dimensions are fairly long.

The neck dimensions of the chamber are also very generous.

The rifling is six lands and grooves and the twist rate is about 1:13.5"

Using my standard 58 grains reloader 15/285 grain prvi handloads, the primers look like fired 30-30 primers, not flattened whatsoever. The same fired cases from my CZ 550 show higher pressure.

Clearly this almost 100 year old rifle was designed for harsh environments and sweltering heat like in Africa.