Need Help to Identify Brass Case

[albayo]

I have a number of brass shell casings that have a base the same size as a .50 MG at the base, and has straight walls like a shotgun shell. The base is rimless like a .50 and is about 1/8" shorter than the .50 brass. It has been fired as the primer has been pierced. The base is marked IVI, 80, C67 and is 3 3/4" or 95mm in length. If anyone knows what they are for I would appreciate your help.
Thanks
Al

 

[Doc M]

Pics or it didn't happen.

Or, rather, pics or we may not be able to help you.

-M

 

[Dosing]

From a previous thread

I was under the impression that the Cartridge for the 12 pdr is the Cartridge Calibre .50 Blank C67 for 12 pdr 8 cwt gun. Can you post a pic?

They both are,, the C128 is rimmed, and the C67 isn't.
The C128 is the replacement for the C67,, the C128 being designed to be more easily removed from the 12pdr casing adapter.
I don't have pics, but they look the same except for the rim.