Cartridge Case Tumblers
When previously-fired cases are used, they must be cleaned and inspected before loading. Cases should be polished in a tumbler to remove oxidation and allow easier inspection of the case. Cleaning in a tumbler will also clean the interior of cases, which is often considered important for handloading high-precision target rounds. Look for cracked necks, non-reloadable cases made of steel, aluminum, or Berdan primed cases, signs of head separation are all reasons to reject a case. Cases are measured for length, and any that are over the recommended length are trimmed down to the nominal length.

Tumbler media made of crushed walnut shells or corn cobb is used in the tumbler to clean the cases.  Walnut shells will clean more quickly and is best for heavily tarnished cases leaving a satin finish.  The corn cobb media yields a higher degree of shine in the way of a more polished finish.