The comp on my 9mm PCC barrel was badly leaded after only 45 rounds of my PC'd boolits and scraping and brushing did little to remove the accumulations. It was on another forum that I read about a 50:50 mix of vinegar and hydrogen peroxide so I hung my gun barrel down from my workbench pegboard with only the comp submerged in the solution. It sat immersed for a total of 8 hours and was completely clean after some wiping with a paper towel. I also read that if you spray your comp with any lanolin-based case lubricant, lead will not adhere. That I have not tried but plan to do so soon.
My only question is if the barrel bore is not showing any leading, why is it being deposited in the comp? Lead is not being 'shaved' off the boolit as it passes through the comp. The lead appears to be an accumulation of very tiny particles that are being 'sprayed'. It is a VG6 Epsilon if anyone is curious.