My real question is, who sloshes enough bore cleaner on the outside of shotgun barrels to ever compromise the rib solder joints?
A lot of ribs first loosen right up next to the muzzle end...I attribute this to solvent.
Part of the answer lies in the name "solvent" with out looking it up I'm betting it means to penetrate and dissolve.
Nobody I know cleans their doubles from the muzzles. Most folks will wet a brush or patch and run it in from the breech with the muzzles pointing downward. Any small amount of excess bore solvent will run around the breech area, or drip out of the muzzles. I put newspaper on the floor to catch any drips because drips go down due to gravity. Unless you are doing this muzzles up, virtually no bore solvent will be getting onto the ribs around the muzzles.
Solder joints usually fail because they were not all that sound to begin with due to poor prep, materials, fluxing, or temperature. Ever see a high speed video of a gun firing and see the violent flexing and movement at the muzzles? Little wonder many rib separations start there. But they also commonly happen where the lower rib meets the forearm loop, far from any inadvertent sloshing of solvent during cleaning. The name "solvent" has nothing to do with it. Water is known as the "universal solvent", but my fishing sinkers aren't dissolving in it, and my soldered copper water lines aren't falling apart. And hunting in the rain hasn't popped my shotgun ribs.
