Smurf,The method I used to repair the barrel sepereation was to clean both sides of the separation using 3000 grit sand paper, used flux on both sides, I then secured a damp (not dripping) cloth with wire 4-5” behind repair area (this damp cloth drew heat away from existing solder), hung the assembly with muzzle down, heated area I wanted solder to flow, when it did flow checked opposite side it looked good let cool and checked to see if it held. Final step was cleaning up a small run of solder. Nearly 1 year later and all is still good and my son shoots it almost weekly.