Has the barrel sprung away from the saddle that much or are you exaggerating the gap for the purpose of the photo? If it is naturally sprung as much as shown in the photo then the solder is being asked a lot to keep the barrel muzzle attached to the saddle, there is quite a lot of force involved there. What is causing that amount of deflection if indeed it is natural? If the muzzle does sit down onto the saddle then a good epoxy for reattachment could work without affecting the bluing or other nearby soldered areas such as the front sight etc.