From the case design, the head is a European “Mauser-A” head, and the primer is a common late 1900s BP diameter ( .245 to .255), with .250 being British and .254 being European. The use of three Flash holes was also not unusual in large BP cases of the time.
I would venture to say that is is a 11 mm Blank (is it crimped, or simply wadded and mouth rolled?..what is the Head Diameter? if it is .515, then it is a Mauser ( 11mm or 10,15 Serbian)…if it is .530-545 it could be for a .43 Spanish,a 11mm Gras or an 11 mm Werndl or Mannlicher; even some other “11mms” would fit this Blank ( I use WCF .40/82 cases to make 11mm Mauser Blanks (Movie use).
ON the other hand, it could be a Launching Cartridge (such as for Signal Flares or for Ship-to-Ship Line throwing. We know of British and US use of their BP cases for such use, so why not the Germans or the French, in their respective Navies?
The fact that is is “Unheadstamped” could point to any late 1900s Manufacturer…US, European, or British, for “Export orders” to most anyhwere in the world. ( yes, US Makers did make Berdan-primed shells as well as Boxer Primed ones, in the 1880s-1900), especially for Latin American orders.
Any other suggestions…Hola, Fede, Did Argentina buy any 11mm Spanish or other Blanks of this type for their Rolling Blocks or Gatlings?