IME BBS isn't better then numerous solvents available, it does the job for fouling other then copper. For copper you need something dedicated be it sweets, foams, JB's, etc. Some solvents such as: SC MC#7 willremove trace deposits of copper but run a patch of sweets behind and you'll find out how little it really does. Though in a ML copper isn't usually a concern on the account of sabots being used with most copper jacketed bullets.

As far as the water/soap cleaning, its works for me.I dry swab immediately, coat liberally with sheath and store on a rag muzzle down in my gun cabinet. No problems to report in doing this for many years.