I chamber sleeved a Fox 16 down to 20. The chambers had been heavily pitted because two paper shells had been left in them for decades. They had to be sleeved to save the barrels. I decided to go down to 20 ga. as I had other 16's exactly like the ruined barrels, 30" f&f. Having a extra set of 20 ga. Extractors on hand helped. Plus I liked the 30" barrels thinking they would make a great long range dove shooting setup. Plans were to restock it for sporting clays and. Ate season dove gun. That has not happened yet but hopefully one day......
I've thought about chamber sleeving 10/12 on several guns. It just makes the ammo situation so much easier. Plus I can reload from components on hand, low pressure loads which would give me a lot of flexibility in shooting situations. The only thing that's has held me back is weight. I don't shoot that many heavy doubles these days. Given equal choke and fit I just go with the lightest gun. Most tens are heavier than a 12 made in the same period. I'd try using 10/12 chamber adapters to see if you like shooting the gun as a 12 before you invest too much time and money into the project.
