49, Are the barrel dia. you have given measured at the muzzle or in the bore itself. The proof marks of 16/1 and 14/1 are very unusual for a 12 ga. gun, particularly the 16/1. I have never seen that tight a bore proof mark on a 12??? Those bore sizes if they are the bore, not at the muzzle,would be more appropriate on a 16 ga. not a 12. Something not quite computing there.Could it be a 16 that has been re-chambered and proofed to 12 ga.??

Better to keep your mouth shut and be thought stupid,than open it and confirm.