12ga x ? Trying to narrow down the search for the rifle caliber. Nothing in my copy of The Handloader's Manual of Cartridge Conversions. quite fit. Closest is the 11.15x36R Werndl carbine. Dimensions of the cast follow.
Length of case = 1.41

Cal = .43

neck of case = .457

base of case just above the rim = .475

rim thickness is .073

rim diameter is .535

Any and all help greatly appreciated.