I have no wish to start an argument here, but the information given above, re temperatures, is incorrect. Most silver solder alloys have a FLOW temperature between 1000F and 1200F. Brazing flux will generally turn clear and active at about 1100F and the filler metal(bronze alloy) will flow readily between 1150F and 1450F, depending upon alloy. Virtually all barrel assemblies are oven-brazed in a controlled, inert, atmosphere,or in a vacuum, in order to eliminate contaminates.
The old-timers at Purdey's used to hold an empty tin upside down and hold a burning candle beneath it, in order to deposit the lamp-black on the bottom of the tin. They then added some clear lacquer, mixed in the lamp-black with a very small artist's brush, and painted that mixture along the solder joints.
