George Nonte mentions a 9X58 1/2 Sauer in his book "Cartridge Case Conversions". He recommended using 32-40 brass, which resulted in a case .125" too short. For a full length case, he recommended trimming down a 9.3X72 case. He lists a rim diameter of .498", a head diameter of .433". a neck diameter of .385". He also describes it as a black powder cartridge.