RE: Looking For Fouling
Reasons against bronze brushes.
One, its abrasive. And abrasive use of things down the barrel has always been frowned upon. In other words, why create more wear when you do not have too with the chemicals available today. Two, unless you use a new one down the barrel everytime, you putting the same gunk down you barrel. Three, it reacts with most ammonia cleaners, and causes that blue residue, and not only gives false indication of copper, but will also puts more gunk down you barrel.
with all the cleaners out there, there really isn't a need for the wire brushes. I use the nylon ones if I feel the need, and do not use the same one twice. If you ever looked down a nice Dan Lilja barrel with a borescope and then down after a hard day of brushing with a bronze brush, you can see the scratch marks.
Maybe it makes a miniscule diffference, but if I don't have to use it, why do it?