PWM: Here are the measurements off the Cerrosafe chamber cast:
Length, 1.95 inches. Rim: .600. Base: .518 Shoulder: .524. Neck: .485 diamter and about .465 deep. Rifling is seven-groove Henry style, and .448 is the smallest I can measure with the odd groove.

I recently came into a little Belgian cape gun and the rifle barrel seems (according to the chamber cast) to be chambered for the 11.15 X 50R cartridge, which is essentially the 11.15 X60R ".43 Mauser" with a shorter neck. Anyone have experience with this old BP number? Do you just use .43 Mauser dies and shortened cases? Thanks for any comments or advice.

I could be wrong but I think you might have an 11x50R Belgian Albini M67/72. Albini rifles used "lift block" actions. Another similar round was the 11x53R Belgian Comblain, but these were used in falling block type rifles employed in some South American countries.

bill, this is a case for a kraut, we know over hundred different cases made from 11,15x60 R.yours is maybe one of this. please give more measurments, have you made a chamber cast and slug the barrel? 11,15x50R is maybe the old werder rifle cartridge,in fact the mother of the 11,15x60R. of course a blackpowder number.
this is a rare chambering,allmost any of the werder rifles are rechambered for the mauser cartridge.

Craigster: I don't think it is either of the Belgian military numbers, as the base is .518 and the rim measures .600.