Mike:
Congrats on taking the risk on a nice find though. Maybe I shouldn't have used the terms boring or wear because the current measurements are less than what you would think the original to be unless you consider around 1868 a 12 1/2 bore to 13 1/2 bore could be stamped 13 depending on the discretion of the plug gauge pusher. So there had to be some sort of modification. I have a similar Thomas Bland and Sons w/ a 14 bore stamp, a later number 16 stamp but it accepts 12 bore. Mystery for now.
Kind Regards,
Raimey
rse
