What scale preventer to use on a barrel

[Randy in Arizona]

I need to silver solder a sight base onto a barrel and would like some advise on what scale preventing compound to use in the barrel and on the outside to keep from damaging the rifling or the bluing.

 

[mete]

Are you talking about silver BRAZE ? Solders melt at under 800F and brazes melt at over 800F.Bluing must be removed to solder or braze. The fluxes should do it but it's best to sand it off. If you do it quickly brazing with an O/A torch shouldn't be a problem inside the barrel.The outside you will have to do some refinishing .Solder will not be a problem except that the flux will remove any bluing it touches .

 

[Sunray]

You'll have to remove the bluing(emery cloth works well) on the spot you're soldering the part onto, but other than that, you don't need to do anything else. You don't use enough heat to bother the bluing around said spot and certainly not enough to even scare the rifling. A regular propane torch will do nicely. The only remotely difficult part is getting the base on the barrel, top dead centre.