Justin,
I don't think the bore was ever .719 or .729-.732 (standard 12 bore diameter) ...I think it was some variation of barrel/choke design that used .770 wadding...just as the inside of a brass 12 gauge shell is also .770...this was a high stakes gambling gun where any technic that increased scores would be used whether it was standardized or not. It's not too far out to think that a high stakes live bird gun might be specially bored or even experimentally bored. The bore diameter 9 inches from the breech is .770
The wall thickness 9 inches from the breech is .092
Mike,
I agree the gun appears totally safe to shoot, but I haven't yet accepted .719 thinking...lagopus said in another thread that anything over .729 is out of proof in British terms...I couldn't wrap my head around that because that would make every L C Smith ever made out of proof with the standard bore diameter of .732...that figure is from Bill Brophy's book on plans and specs of the L C Smith.
I have no problem with a competition gun being bored at .770...the part I don't understand is why it was stamped 13/1...
A interesting side note about experimental bores....
Experimental bores interested Charles Newton (c1920) and it was reported that he was seen shooting a double-trigger, side-break, boxlock, over & under, 16 gauge at over 2000 FPS, minimizing the need to lead flying targets...although I have a Newton Arms shop floor drawing of that American made (Britte & Britte type) over under, I've yet to see one or even photos, but I have a pretty good idea of that particular gun's last known address...and of course the name of the gunsmith who made it...So if you ever see a side break with no proof marks, you had better nail it down (every super Britte or Paul Scholberg side break is Liege proofed)
