Hi I have found that adding some automotive compound to my media does a incredible job in only a half hours time, and no matter how nasty the media looks they come out nice inside and out, they end up having a very dull finish to them but they are spotless, then I put them in my clean media with the polish additive for a half hour and they come out like jewelry and the clean polishing media stays nice alot longer because it's only polishing and not cleaning at the same time, I have cut down my case prep cleaning to 1 hour, there are three grades of compound soft med and rough, I use the rough due to the fact that it is brass and not an auto paint it has more scrubbing power, I can't stress the fact on how nasty the cleaning media gets because of the thorough cleaning, sometimes I pick up the nastyest range find brass I can find and throw it in for spite along with other stuff I am prepping and am shocked every time at how impeccable they come out.
Thanks Dean