I ran across this website where various brands of copper fouling remover were tested by a gun store. Results were not what I expected! The method they used was to weigh a particular copper jacketed bullet before and after submersion in the fluid being tested for a number of hours to see how much weight in copper was stripped off. One, and only one clear winner!

http://www.laniganperformance.com/kg12testresults.html

I make no claims as to the veracity of their testing methods, so please don't flame me for simply posting it. I just found it interesting.