AMtrico,
Back to your original question of why the difference between the 8.7x 72 and the 9.3x72. The 8.7 was the proof house's measurement of the bore (not bullet or groove) diameter and the 72 (in mm) was the length of the longest cartridge case it would accept. The 9.3x72R is the name of the cartridge the rifle barrel is chambered for. There were 4 different 9.3x72Rs that could have the 8.7x 72 proof marks, 3 of which were similar and the other (9.3x72R Sauer and Sohn) was an entirely different cartridge, more similar to the 9.3x74R. The (9.3x72R E [English form] and 9.3x72R D [ German form] and 9.3 x72 N [ normalizert/ standardized]) other three were all very similar, differing in minor case shape and rim thickness. The 9.3x72R N was designed to allow chambering new rifles and rechambering older rifles to safely fire the standardized cartridge. The older rifles often had barrels with differing groove diameters (I have seen them from .352" to .368") and the Express bullet Hoot described was designed for the standardized cartridge, to be safe in any of them. Because of this and the standardized cartridge was loaded to the same pressure as the older cartridges; the rechambered rifles did not have to be submitted for reproof. Every once in a while, we find a rifle still chambered for one of the older forms of the cartridge, but other than this we can't tell what the original chambering was for any of the early ones. As Raimey mentioned, cast bullets do well in any of them. We find a lot of them with groove diameters of .357"-.359" and 35 caliber rifle bullets or 38 caliber pistol bullets can be used in them. The 9.3 bullets intended for such cartridges as 9.3x62/9.3x64/ or 9.3x74R should not be used, but some bullet makers produce a "softer" bullet especially for 9.3x72Rs that can be used if the diameters match and if you can find them the Express type of bullet is always useable.
Mike
