Clean, attractive brass should be the goal of every reloader.
Cleaning brass by tumbling is the economical, safe first step in assembling quality handloads.
Besides ensuring long life for the most valuable component of your ammunition, cleaning your brass will help reduce wear and tear on your expensive reloading dies, not to mention the chamber of your firearm.
Grit and grime from uncleaned brass can become imbedded in the inner surfaces of your sizing dies, scratching and marring every subsequent case.
The same grime can be expected to accelerate wear in the chamber and feeding system of your rifle or handgun.

(Walnut cleans better than corn, corn polishes better than walnut)