German guns are a law unto themselves. That said, most of the 9.3x72R drillings I have measured have a groove diameter of approximately .360. This is great because it means you can generally use 38 pistol bullets. My favorite is the 200 grain Hornady XTP; shoots accurately, is easy on the bore and performs very well on game. Huntingtons has 72R Norma brass. Loaded with H4198 powder and dacron over-powder wadding, they give a very nice smokeless-for-blackpowder result.

Good shooting.