If the barrels of this gun are marked as you say: 11 & 12 bore, then I would suggest you measure the bores to see if they mic out to an actual 10-bore.
It is my admittedly remote suspicion that this gun may have been a 12 bore, rechambered to 10 bore -- with undersize 10 bores being the result of honing out 11 and 12 bore barrels to clean them up.
Just to be safe, the barrel wall thickness should also be checked. Especially if a 10-bore rechamber job cut cones out too far.
This is all speculation from a distance. If the gun shoots well, it's probably fine.
|