Newer guns have better solder obviously, or even silver solder. Hell hi-force 44 is 96% tin, and Im still not convinced that any long term use of any solvent, other than something that is definitely not designed for wiping guns barrels down with, is going to loosen a rib. I say we do a mythbusters test on some old scrap guns. Chuck, dont you know somebody with a bunch of barrels? Lets soak them in a variety of "solvents" and see what happens.