Robert.....you are correct. Many barrels are made from 12L14 steel, which is a leaded steel. A small amount of lead is
added to the steel in order to make it more machineable. And, Sydney, you have the soldering method described quite
well, the way I do it, when necessary. Years ago I made a simple soldering device to hold either an underlug or a front
sight in place, also has spring tension to push it down when the solder melts. I took a piece of 1/2" x about 6" long,
bent both ends down (1/2") at 90 degrees. I then filed one end to fit a round barrel, the other end has a slot to fit over
an underlug or sight. After you have the sight or underlug tinned, you merely hold it in place by positioning this little fixture over the object, place a parallel clamp over it in the middle. There is enough spring in any kind of steel to keep tension on the object, when the solder melts it is pushed down automatically. You will also find that if it does not seem to
be located properly, you can re-heat it and merely roll it to one side or the other....................Don