I chamber sleeved a FOX 16 a few years ago. It had been stored with two paper shells in the chambers. They had absorbed moisture and the chambers were very pitted. It took .020+ to clean out one and .033 to clean out the other. Does not sound like a lot of metal but it was. I was younger and more adventerious in those days. Might not even try the job myself these days. It is harder than I thought it would be and set up was everything to getting a good outcome. All the above mentioned smiths can do a greast job.
I decided to chamber sleeve the 16 down to a 20 gauge chamber. Ended up with a heck of a long range Dove gun. In effect I have a back bored 20. I could have gone back with 16 chambers but I had three 16's with 30" barrels and no 20's with 30" barrels at the time. The collectors value was long gone so I made the gun into what I wanted.
