I saw just the opposite on carbon fouling. Could be the difference in bullet wt.??? My rifle won't shoot heavy bullets well for some reason. Shoots 162ELDX's like a bench gun. Everyone says that bullet is terrible. 1-9 Proof carbon, SAAMI reamer.I tried a pound of 8133 in my 28, I did not think it was any different than Retumbo. I noticed it was dirty in my 28, it was Carbon fouled pretty good after 20 rounds. I use RL33 with 195 Berger and that is the most accurate powder for me and the cleaning was no different for me than 8133. I have not found N570 in stock for years, so I have never been able to test it, but the velocity from what I hear is on par with RL33.