I don't have an 8X75RS, but I do have a Krieghoff combination gun with 16 ga./7X75R barrels. The shot barrel is fitted with a full length insert barrel in 6X52R Bretschneider, which gives me an instantaneous choice of calibers for close range and long range shots.

I also have a Krieghoff drilling in 16/16/8X65RS caliber, and I am quite pleased with it as well. While not as powerful as the 8X75RS, the 8X65RS is no slouch. The ballistics are similar to the wildcat 8mm-'06, which was a popular cartridge immediately after WW II, when ammunition for 8X57IS bring back Mausers was hard to find.