Brittany Man, let us see a specific example, a Bretta 626 with a badly bulged barrel. It was deribbed, the Monobloc was gently heated and the barrel knocked out. Yes, nowdays you cannot buy profiled tubes easily in Europe, so a semi fiished tube from Effebi was finish profiled on a CNC lathe and internally honed on a modern honing machine. It was solder tinned and inserted in the monobloc and then chambered with a Clymer reamer. As the new tube was not chromed, and the barrels were to be reblued anyway, the other barrel was dechromed and honed as well and the forcing cone lengthened with the same reamer. The job thus far took two days and the smith had time to do other things in the meantime (one being to take care of my broken V spring). The rib resolder took longer, the rust bluing had its own schedule but the whole thing was done in about a week.
Last time I looked, the British time and cost for such a job was in the hundreds of pounds for sleeving and thousands for rebarreling and the time quoted was in months.
Sleeving looks like monobloc work, but it is not. One reason being that chopper lumps are machined before brazing and the flat (braze) side may extend further out than the chamber. When sleeving the breech ends must be cut off at a point that offers free and round breech ends to receive the new tubes step. Hence the breech ends in sleeving jobs vary in length, the cut off point being determined by the point where the barrels are free from each other. And once you sleeved your chopper or dovetail barrels you end up with a multi part assembly which was never designed to be this way.
