Drew, that is the correct text for the JM, thanks.
So based on what you see here this gun was made after 1853 "Perron" and before 1877, which is a nice way to narrow it down.
17.8mm equates to 0.700in, which is exactly what the bore measures, so probably not honed at all.
This gun would then be a 7 thou over bored 14ga.
I do have wads on order, there will be a lot more inspection first but based on what my local smith said I should be able to shoot light loads without concern, I doubt I will ever shoot heavy loads in it.
