From what i could find out about it, it comes from germany, and dates back to about 1904.

My father has one and its a good low pressure cartridge, with manageable recoil.

Its still very popular in europe since its an appropriate caliber for large deer and has everything going for it for use in a double rifles.

Its funny because there isn't huge selections of game cartridge popularity in europe, not what you see in the states, but the ones that are popular, have been so for a long time, and seem to be almost oblivious to what people use in the states. Its a similar story with RWS magnum cartridge 8x68S. Popular in germany, but almost unheard of in australia, and more than likely not popular in the states.

The only comment i have on the 9.3 is that you are going to have to reload yourself. Ammo is very expensive (on what i could find in australia, prices are about $AUS7 a round, or around $150 a box of 20) and brass isn't cheap either, but you save a fair bit of money in the process.