I changed the pictures but for the life of me cannot figure out how to make them bigger!
If I resize them in photobucket, they loose their clarity and look terrible.
If Curl can resize them and keep them sharp, that would be great!

By the rim/base diameter, I would rule out the 360 2-3/4", 2-1/4" and the 2-7/16"
I have ordered more cerrosafe so I can take a cast this weekend.

If Fraser rebarreled it, they stamped it with the same number as the action. That is the origin of my question about the existance of a BP cartridge of similar dimensions to the 400/360 because this barrel isn't nitro proofed.