To be honest, I don't see the advantage of having a DR caliber 425WR when there were other cartridges at that time that were much more suitable for this type of weapon.

The cartridge 425WR was a compromise in design to fit it into a Mauser 98 action, like some other cartridges of the time. The rebated rim of this cartridges can even cause problems when reloading, what is not ideal by Big Game hunting. Apart from the technical performance, I cannot understand the effort to adapt such cartridges to a DR breech action.