12.17x44 might be the same as Husqvarna's 12.2x44R, which they oft chambered in their side by side, shotgun rifles.

It is the Uro version of the .50/70 US ctg.

Yes-Quite likely .348 brass could be used, but they are quite a bit undersized in the base to .50/70 - they do work, though. As well, shortened .500Nitro brass also worked when shortened, and with the rims punched forward in 4 places for proper headspace due to their thin rims.

Barnes Ctgs. of the World lists measurements on the 12.17x44 Remington M67 ctg. for Sweden and Norway, noting it is the Euro version of the .50/70.

Barnes lists base diameter as .546" and case length as 1.73".

My brand new unfired .348 Winchester brass measured exactly the same, .546". There ya go!