Intro Guide To Polishing Brass For Reloading

The first stage for reloading cartridges (Pistol or Rifle) is cleaning the brass. If you are using virgin brass you can skip this step, but otherwise this much debated topic is your starting point. Your first and foremost concern should be safety. You are working with dangerous components that require care when handling and a well ventilated area. Before we get started, lets talk about a few reasons to clean and polish your brass, prior to reloading. The two primary reasons are for inspection and reducing friction in the reloading process. Whenever reusing a case, you need to insure it does not show signs of excessive pressure or over use. We will discuss warning signs in another article. The next reason is wear and tear on the reloading machine. Clean brass puts less wear on dies and requires less friction to load, providing a more consistent finish. Just how clean does it need to be? That is a matter of personal preference and highly debated. Some people use a multiple step process to render the brass spotless with a mirror finish. Others say just wash the dirt off and go for it. From our experience the best answer is somewhere in between. The goal is clean brass with no signs of carbon build up and minimal, to no tarnish.

Brass after tumbling
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Above, you can see a typical example of spent shell casings. They have a dull finish with signs of carbon around the case mouth and a layer of carbon inside the case. The first step in our process involves washing the brass. If it is a small quantity, simply place the brass into a one gallon Ziploc bag. Fill the bag half full with hot water and a single pump of Dawn dish soap. Agitate the bag a few times and let the brass soak 5-10 minutes before rinsing with fresh water. The reason for this step is to help minimize the release of airborne lead. While many people will debate the need for this step, we insist that it is a necessary precaution that only takes a few seconds. If you reload, we highly suggest you periodically test for lead contamination in your work area. A simple kit such as this 3M lead kit, will either put your mind at ease that your work station cleaning procedure is adequate, or tell you that you need to improve your cleaning regimen and be more careful in the future.

Washing brass before reloading
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With the brass finished soaking, now is the time to lay it out to dry. If you do not wear gloves for this step, wash your hands immediately after finishing. It should also be stated that smoking and eating should always be avoided whenever handling casings, as there is an increased risk of transferring lead from your hands to your lungs or stomach. I usually place the casings I want to reload in old ammo trays. This allows me to easily inspect the brass while at the same time confirming its caliber. In the image below, you cans see that there are a few 10mm rounds mixed in with the bulk of the rounds, which are .40. Now is the time you want to find this out, not when sitting at your press dealing with some form of equipment malfunction.

Dry brass
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While the brass is drying, start preparing your tumbler. I suggest doing this outside for the lead concerns stated above. So far, our favorite mix is one liter of crushed walnuts and two tablespoons Mothers PowerMetal. The crushed walnut can be purchased at your local pet store in different sizes and is usually marketed for bedding use. The polish is not that difficult to find in most areas, but can be ordered off-line here for less. The reason we suggest this polish, other than in our opinion it works awesome, is that it is ammonia free and will not weaken the brass. With the polish added to the media, turn on the tumbler for 5-10 minutes to distribute the polish evenly.

Load up vibrasonic tumbler
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With the polished mixed in, now add the shells. We recommend leaving the spent primers in the casings for this step. This prevents any of the media from entering the flash hole of the primer pocket, which you will have to dig out later. A common question is how many shells should you polish at once. This depends on the size and power of your tumbler and the finish you are seeking. If you add excess brass to the point that it bangs against itself, you will end up with a satin finish. While this will not hurt performance, it may not yield the mirror finish some are looking for. I have had good results keeping the ratio of shells to media to a 1:3 by volume ratio. Your ratio may need to be adjusted based on the power and size of your tumbler.

Load brass into tumbler
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If you are using crushed walnut, 45 minutes to an hour will give you the results shown below. It is best described as a gloss satin finish. If you want something with more of a mirror finish, you can run the brass for an additional hour in a  crushed corn cob media. While you can start with the corn media, this will increase the total polishing time. As is usually the case, polishing is best done in steps. If you do opt for the one step corn cob method, reported typical tumbling times are usually around 4 hours. If you do use corn, be aware that the crushed cob you typically find at most pet stores will not work very well. It contains chaff and other bits, not just the pit. If you use corn media, it needs to be blast media, not pet bedding.

Dirty brass prior to tumbling and after washing
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While several companies offer media separators, we have found that fryer baskets, such as this one work just as well. They also allow us to have several inexpensive baskets around for different media. Again, keep in mind safety in this step. The media will be loaded with lead dust. Once you have removed your casings, you can set aside the media for reuse later.

Brass tumbled in dry walnut media no corn
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A lot of people have reported that tumbling their casings does not clean out the inside of the shells. Above, you can see shells that were tumbled for one hour in crushed walnut and as reported, the insides are not clean. For pistol and non-precision loading they are clean enough, but there are cases where you may want the insides cleaned also. To accomplish this, there is a simple trick, water. Once you have loaded the media into the tumbler along with the polish, add water until all of the media is wet and a thin layer will float out on the top when the tumbler is on. The casings below were run in this way for one hour in the media, followed by 5 minutes using only dry walnut media to remove the film left by the water and polish. You can clearly see the difference inside the shells.

Brass tumbled in wed slurry media
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Whatever method you decide to use, exercise care and safety for both yourself and those around you. If you are not comfortable with a step, ask a more experienced reloader, or post it up on our forums. Have fun, and let us know if you find any other tips for polishing or secret recipes for polishing media.


Polished with rice and media
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After seeing a lot of talk about using brown rice as a polishing media, we decided to test it. We also tested Flourite as a faster option to walnut shells. In the above side by side image, you can see that both media produced a satin blasted finish not a shiny one. Some people prefer this finish, so it does have its place. Both batches were run 1 hour in a vibrasonic tumbler. The rice was run dry and the Flourite was run with 2 cups of water in 4cups of Flourite. The Flourite media had the added benefit of cleaning the inside of the case as well as cleaning up very easily. Although it is more expensive than walnut shells, it would make a great one step polishing media if you are looking for a satin finish.  The rice on the other hand did little to the inside of the case other than coat it with a layer of powdered rice and plug up the flash hole even though the rounds had not been de-capped. If there is anything else you would like tosee tested let us know.