Dixon cartridge tool.

This is the cartridge tool I mentioned in another post, made by Dixon & Sons who manufactured several types of gun tool. It is stamped 12 and a 12 gauge cardboard cartridge fits over the end of it. The round blade is very shape and can be rotated as sections become blunt and eventually replaced. There is a spring to hold the blade against the notch, this has become detached. 4 inches long. Although I am not certain, I think it is for trimming the uneven end of a cardboard cartridge before reloading.