The following guide for steel shot burnishing provides some basic guidelines prior to using steel shot in either a vibratory tumbler or barrel tumbler.
Burnishing with Steel Shot in a Vibratory Finishing Machine
Burnishing with Steel Shot in a Barrel Tumbler
Procedure for Cleaning Dark or Lightly Rusted Steel Shot
Rinse out barrel. Add sufficient fresh water to cover the shot by one or two inches. Add one teaspoon of Kramco 750 to the barrel for each gallon of water. Run for one or two hours. Repeat if shot is not bright and light colored. Rinse out after run. You can now begin normal burnishing process.