I have had about 10 soft-solder sleeved guns dismantled and TIG sleeved. Although the guy who does them always warns of the possibility of being unable to get them apart, he has always managed it so far! Guns must be reproofed after this process.
I understand all that Gunman says about the difficulties with this but it is about 1/2 the price of sleeving with fresh tubes and has always been very successful so far.
The one gun I have come across that had been TIG welded without removing the solder first was a disaster: a mass of blow holes. With very careful 'buttering' of mild steel filler rod and repeated striking up, we finally managed to achieve a clean finish but it took about 5 goes. The gun was of course reproofed afterwards.
In re-blacking soft-solder sleeved guns I often find it very difficult to lose the silver line. Never has this been visible solder, just oil leaking out of the joint causing the rusting solution to not take. Also I suspect that the flux trapped within the joint also leaches out and produces the gray gradient around the joint on some guns that gets progressively worse over the years.
