No, I was talking about the 6.5 Dutch mannlicher cartridge, known as the .256 in the UK.
I am very much aware that this is what you had referred to (Parabola also did). And indeed this is a fine ex-military (Romania as well as the Netherlands) and equally famous civilian cartridge. The NRA museum also houses a fine Camp Perry match rifle in this caliber.
However, Parabola's own question or musing had referred to an unnamed European "6mm rimmed" cartridge. And I found it finally, about 84 years earlier than the 6x62R Frères. It is the rare 6x58 R Förster around the turn of the 19th to the 20th century, maybe best comparable to the old 6mm Lee Navy.
P.S.: its rimless brother, the 6x58 Förster, was much used by the last Kaiser (Wilhelm II.).
Carcano
