Sleeving usually describes cutting the barrels off just ahead of the lump (the hooked piece that the barrels pivot on) and then turning down the breach end of donor barrels and boring out the recipient barrels so that the donor barrels can be slid inside and soft soldered together. It also requires removing the original ribs and using it to refasten the new barrels together. I have done it once or twice and it is not something I would suggest without significant machining experience and a lathe plus a soldering jig to support the barrels during soldering the ribs. You could probably buy 2 or 3 antique guns for the cost of having it done commercially.
Another option is to purchase Briley tubes which are full length tubes or barrels which fit inside your gun. I have not seen any prices recently but would expect them to be several hundred dollars although cheaper than commercial sleeving. My impression of 10" long chamber inserts is that they usually go down 1 guage size and you would want to be sure that they will fit your barrels before buying them. I am guessing there must be some sort of choke built into the 10" tubes. I say that because during the long gun registry, I tried sleeving a (cheap) 12 guage pre 1998 gun's chambers to accept 14 guage Greener Police Shells (which I made from Winchester AA shells). The result might have been good for clearing bar rooms but definitely not much else. To say that the pattern was open is an understatement. Why would I do it, you ask? By changing the gun to 14 guage it was legally an antique and I would not have to register it.
cheers mooncoon
