Jim:

Before I reload a case, I tumble clean them. They come out, in addition to being clean & bright, with a very slight coating of case cleaner (I use the Midway brand) & feel "slick". There is no discernable residue, nothing to come off & building up in the neck or leade, just a polished, slick surface on the case. I believe this promotes good feeding through the mnagazine, especially in semi-autos like the Garandicon & AR15.