Stephen,
With the exception of 9.3x72R Sauer & Sohn, mentioned above, the others are basically the same and were all based on the British 360 2 1/4" case (as were other similar cartridges differing mostly by length, from 48- 85mm). There were no mandated standards when this development was happening, and it seems as though each gunmaker had its own idea as to the best shape and length (volume) as well as bullet diameter/weight. The most popular length seemed to be 72 mm, so this will only address that length, even some others have similar shape. One of the cartridges was actually called 360x72mmR. Two other main versions were the 9.3x72mm R-E (English version) another was the 9.3x72mmR- D (Deutsche version, this is the one that seems to cause the most difficulty in determining which cartridge to use. The taper seems to be a "sweep" rather than a straight taper. I think, without proof that this form may have come about by making a 9.3x57mmR chamber with an existing reamer and then extending the neck with a straight reamer until the case length was 72mm. When new reamers were required, they would have made them with the straight extension.). This caused enough confusion that one of the first attempts at standardization was for the 9.3x72R (also 8.15x46R). A standardization committee worked out a set of dimensions that would allow
most if not all the old rifles to use a common ammo. The result of the effort was the form known as 9.3x72R Normalizert (or Normal. often shown as N), this means Standardized. They standardized the rim dimensions, case shape and dimensions, and, importantly, standardized a bullet that would work with varying barrel diameters (this is the 193-grain flat nose jacketed bullet in today's commercial ammo). An examination of this bullet will show that the main diameters are for the smaller barrels but had a "driving band" to adapt it to the larger barrels while not producing undue pressures in the smaller ones. Importantly, existing rifles could be rechambered to the normal chamber dimensions by the local gunsmiths, without the necessity of resubmitting it to the proof house for a crown R repair proof. This left many rifles with different barrel diameter barrels, chambered for the normal cartridge. It wasn't until the 1939 proof law that the common name of the cartridge to be used was required to be on the rifles. By that time, there were a great many 9.3x72R normal. rifles existing, but few to none were being built (and marked) because they were prohibited for "Hochwild" (Big game). It is confusing, but it fun to work with and use.
Mike
