well I don't have my books handy but it was originally proofed as a tight 12 indicated by the 13/1 then at some later date the bore was opened to .729 a standard bore for 12. 2 1/2 " chambers, 3 tons per sq and 1 1/8 are pretty normal for a 2 1/2" chambered gun. Obviously Nitro proof and is has some choke not cylinder bore.


This ain't a dress rehearsal , Don't Let the Old Man IN