It's a W C Scott 1887 Damascus black powder prof. I will measure today the diameter of the chamber for the shell if I get some time. I measured the bores and by my measurement it's .735 which I assume means it's been honed.But what I I guess I don't understand about the 13 is what was the theory of the 13 gauge.More metal to hone?It also has a tiny 13 over a 14m which I think means choke but it goes from .735 to wider when it gets to the the end of the breach.

monty