A combination of factors...
Had Germany won the First World War, German East Africa (Tanzania) and German Southwest Africa (Namibia) would have remained German. Kenya and Uganda would almost certainly have been ceded to Germany as well. The interwar years were the period when Safari exploded in the West. However, under German control, American sportsmen travelling to any of the classic safari destinations would have been met by a PH named Hans or Jurgen rather than Phillip or Harry. Those PHs would have been carrying OU or bolt action rifles in heavy metric calibers. SxS British rifles and calibers would have become a historical oddity noted perhaps for their use in India.
Exactly! And the small and medium metric calibers would have been (are) every bit as good as the fractional calibers that became lore in the English language culture...
- 7x57: needs no introduction. So good that the Brits simply renamed it .275 Rigby...
- 8x57: needs no introduction. Two world wars. Similar in field performance to .30-06...
- 8x68S: better than the .300 H&H magnum and every bit as good as subsequent .300 magnums...
- 9.3x62: needs no introduction. Maybe the closest thing to the mythical single caliber to do it all in Africa...
- 9.3x64: aficionados consider it the only medium caliber likely better than the .375 H&H...
- 9.3x74R: ballistic twin to the .375 H&H Flanged...
- etc.
A certain Mauser 98 action
But the predominant factor, I believe, in the difference between metric and fractional calibers
in heavy DG calibers, is the fact that the German makers benefited from the endless and dirt-cheap availability of the incomparable Mauser 98 bolt action, and developed everything to fit in it.
This explains why, for example, the 10,75x68 (.423) or the 11,2x72 (.440) shot light bullets for their caliber (~350 gr), which lacked sectional density and therefore penetration (regardless of bullets construction - another factor at play), because case capacity was simply too small...
Schuler corrected this to a point with his extra fat 12.7x70, which was good enough that the Brits renamed it the .500 Jeffery, but its rebated rim forever made it difficult to chamber from a staggered column, and the Schuler rifle had to forego the Mauser magazine and use a single column magazine, which reduced capacity.
The Brits, not having a bolt action capable to rival the Mauser 98 -- do not ever try to fire a DG cartridge from a SMLE (Short Magazine Lee Enfield) action !!! -- had no other choice than to develop the double rifle - and this they did to perfection - which is likely the best type of action, aside from the single shot, to launch large diameter, heavy bullets, because cases can be as long and as fat as needed to contain all the propellant required ... and actually case size was promptly recognized as a critical factor in reducing pressure, which was a God-sent for double rifle actions makers.
British large bore / large case rifle cartridges only appeared just before World War One, after Mauser's British agent, Rigby, convinced the factory to create a new action, the fabled 98 Magnum to solve the case capacity limitation imposed by the standard 98 action. Had Mauser refused, it is likely the .416 Rigby, .505 Gibbs, etc. would have never existed.
So, WWI historic and imperial consequences are certainly at play, but it is my belief that the lack of a British action comparable to the Mauser 98 was also a critical factor, and maybe the predominant factor (?), in the development of the Nitro Express family of double rifle cartridges.
The usual supply & demand market factor
In addition, Germany lacked the British social class that was the primary market for the British double rifle development: the wealthy safari-going Victorian gentry who only conceived of using best-quality rifles. German colonists, like British colonists by the way, were perfectly happy with the dirt-cheap, rock-solid, life-dependable Mauser in 7x57 and 9.3x62 and did not have the financial means to purchase exquisite, delicate works of gun-making art. To them, the rifle was a tool, not a social status marker, and shooting African game was part of a day's work, not a fashionable entertainment.
And indeed history...
And indeed, after World War One, and again after World War Two, there was no real market for German gun makers to use themselves the Mauser 98 Magnum action, not even considering its paucity, because Germany had lost its colonies and everything that lived in continental Europe could be adequately dispatched with calibers fitting comfortably in the standard Mauser action.
Few in America realize it, but probably as many, or more (?), 9.3x62 have been (and still are) sold in Europe for Wild Boar drives as in Africa.
