Which Brass Media Should I Use?
Two Things to Consider
Crushed corn cob, crushed walnut shells, and stainless steel pins are the three types of media used to clean and polishing brass cartridges for reloading.
Each has its advantages and disadvantages. Begin your decision-making by considering two things: 1) the type of tumbler you are using (rotary or vibratory), and, 2) how dirty the brass is.
When to Use Corn Cob Media
If you have once-fired brass or brass that is not heavily tarnished then corn cob media will work to get your brass clean. Corn cob media can be used in both vibratory and rotary tumblers with good success. If you want the brass to come out with a nice bright polish, rather than just clean, you will want to get treated corncob media or add your own polishing compound to untreated corncob media.
How to Use Corn Cob Media
Untreated black walnut shell media is more aggressive than crushed corn cob and is used for dirtier brass.
When to Use Walnut Shell Media
If you have brass that has not been thoroughly cleaned after many reloads or you have some range pickings that are tarnished from beingg on the ground for a long period of time then crushed crushed walnut shell media might work well. Walnut shell is a much harder material than corn cob and it has sharper points and edges needed to abrade tarnish from the brass.
Treating Your Media
If your are going for a bright polish on your brass it's necessary to get either treated walnut shell media or add your own polish to untreated walnut shell media.
Many people use red rouge or TXP aluminum oxide to treat their media. One level tablespoon of polish per pound of media is enough to start. Refresh with another tablespoon after a few batches of brass have been cleaned.
A recommended way to treat your media in a vibratory tumbler: 1) fill the bowl about 1/2 full or media, 2) spoon your polish onto the surface of the media, 3) then cover the polish with the rest of your media, 4) place the lid on the tumbler, then, 5) start the motor and allow the tumbler to run for five minutes. This method will treat the media with very little mess. If you try to spoon the media into the bowl while the tumbler is vibrating, the air circulation might suspend some of the media into the air.
Walnut shell media will work in both rotary and vibratory tumblers. However, we get our best results from walnut media using a Thumler's UV-10 or a UV-18 vibratory tumbler.
How to Use Walnut Shell Media
When to Use Stainless Steel Pins
Stainless steel pin media can only be used in a rotary tumbler such as Thumler's High Speed Model B. This is one of the most effective medias to use for polishing brass in a rotary tumbler. Stainless steel pin media also does a much better job at cleaning the inside of the casing and primer pockets. Using a polish is not required when using stainless steel brass cleaning media as you will be adding a dish detergent or commercial brass cleaning product.