RE: reloading a 300 Ultra-Mag
Barnes CR-10 works well for me also and seems to be a quick, aggressive solvent. But when I want an absolutely clean bore I plug in my Outers Foul-Out electrochemical system. Time saver, possible wear or damage from cleaning rod saver, and odor free. Clean a rifle conventionally then use the Foul-Out on it and see what was missed. Works even better with lead. It is also the only lead remover I use nowadays.