I confess to a long ongoing problem, with no idea as to solution. When resizing brass, I get scratched cases, in particular pistol, but some rifle. This happens with brass that has been fired and cleaned, trimmed, and cleaned, or just brand new. Small particles of brass comes from somewhere, and adheres to the walls of the sizing die, and with my poor eyesight, I'm quite a ways down the batch before I notice that they are being scratched. Then, I remove the die from the press, wipe them out with a cloth patch and Balistol, scrape any tenacious chunks loose, and clean again. A dozen cases later, the problem is back.
Is there some secret of avoiding this problem? I've had several sets of dies ruined over the years from this. I imagine if this is a common problem, the progressive loaders must be pretty bad.