Brass Cleaning Using Stainless Tumbling Media System - Review

By Jason Koplin

Summary: This article shows how to clean brass inside and out using small stainless steel pins from STM, Stainless Tumbling Media. This does not harm the cartridge brass and the results are excellent. A water-tight, rotary tumbler is required along with the stainless media.

I have been reloading for ten years. In that time, I have cleaned many, many, pieces of brass. The method I used for brass cleaning is familiar to many reloaders. I had a vibratory tumbler that I used with ground corn cob or walnut media. There were many days where I would leave the brass cleaning tumbler on for 8 hours to get my brass clean, or at least smooth. I had grown accustomed to my brass, even after 8 hours, being smooth on the outside but dirty inside. Plus, if the brass was tarnished at all, the corn cob media, even the green-treated stuff, would not bring back the luster to the brass after cleaning. Basically, if I wanted pretty shiny brass, I had to start with pretty shiny brass. I simply accepted that the inside would never be clean.


Trying Something New
Recently, while visiting on the web, I saw an ad for Stainless Tumbling Media (STM). I visited the STM website,, and was impressed with the before and after pictures. I had just finished cleaning some range brass and had used up the last of my corncob. As usual, the corncob had not done a great job. The brass was clean on the outside and dirty on the inside. Plus, any cases that were tarnished were smooth but still tarnished.

I decided to give to give the stainless media a shot. It would require an investment, not only in media ($49.99 for 5 lbs.), but a new rotary tumbler ($179.99). The stainless media does not work in conventional vibratory tumblers. But I figured, "What have I got to lose? The rotary tumbler probably works better than my vibratory tumbler, and if it really sucks, I can ask for my money back!" Also the web site said the stainless media "does not work harden, or damage your brass in any way" and the little pins will not remove any measurable amount of metal.

I called Cory, STM's owner, the next day and purchased a Thumblers Rotary Tumbler, 5 lbs. of media and the deluxe separator. Everything arrived a few days later. I opened the box and set it all up.


Impressions of Hardware and Media
The Thumler's Tumbler is a very stout, well-built piece of equipment. It only took minutes to set up. The paint is hardy and thick.The parts are all simple and strong. It should last a very long time. I should note that if the motor ever does die, it takes all of a minute or two to swap in a new one.
The interior of the tumbler is a thick rubber liner. The metal lid has a thick rubber liner too. The rubber does two things. First, it does the obvious, it seals the unit. Its second function was not as obvious, it cuts the noise. This tumbler is much quieter than my old vibratory unit was. You can hardly hear the tumbler, or the shells inside, tumbling away.

The media comes in a surprisingly small pack. Five pounds of stainless pins doesn't take up a lot of room. I was used to having big jugs of corn cob around for the last ten years.


Tumbling Procedure with Water and Stainless Steel Media
1. Setting up the Thumler's Tumbler takes about 10 minutes. It comes mostly assembled, so no engineering skills are required, but you should read the instructions. There isn't a lot to do, but there are a few important set-up details you shouldn't overlook.

2. Pour the media in the tumbler, add brass, add 1 gallon of water, a small amount of liquid soap and a little bit of Lemi-Shine. Watch Cory's video below for the amounts of soap and Lemi-Shine.


Do you have to use Lemi-Shine? Cory says: "Not necessarily. Lemi-Shine is the key to get your brass shiny. If you don't care too much about the shine, then no. It can also help soften the water, which allows the soap to work a little better."

How much brass should you add? Cory suggests putting about two pounds of brass in the Thumbler's Tumbler, which has a 15-lb overall capacity (including water). Here is how that works out for different cartridge types (small to large).


3. Shut the lid tight and start tumbling. Cory recommends one to four hours of continuous tumbling depending on the condition of the brass. After you've done a few batches you can figure out how long it will take for your brass.

4. After tumbling the brass, drain as much of the used, dirty water as possible out of the drum without losing any brass or pins.


5. Next, separate the brass from the steel media, and then rinse off the brass with warm water. (The rinsing stage is important to avoid spots on your now shiny brass).

6. As the final stage, dump the brass on a towel and let it dry.

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SAFETY TIP: For safety's sake, always carefully inspect your brass after tumbling to ensure there are no left-over stainless pins inside any cases. Normally all the pins will drop right out, but in the very rare instance, a pin can wedge in a small-caliber rifle cartridge neck. If that happens just take a small dowel (a chopstick works well), and dislodge the pin.

Here Are STM Cleaning Results — Judge for Yourself

Results of STM Tumbling Are Very Impressive
So this is where it all gets interesting. My first batch was a load of pistol brass that I had picked up at the range the weekend before. Here are some photos of before and after. None of the photos are doctored. I didn't do anything other than load brass, soap, water, Lemi-shine, and the stainless media into the tumbler.

Pistol Brass Cleaning
For my pistol brass. I sorted the brass into calibers before tumbling. If you don't sort, the 9mm cases will stick in the .40 cases, and .40s will stick in the .45acp cases. How well did the STM cleaning work? Take a look at the pictures. First is a photo of some heavily-tarnished .45acp brass before tumbling. The next two photos demonstrate just how well this system works. I was amazed! The brass looks brand new. As promised, the brass is clean inside and out.




Rifle Cartridge Cleaning
The next batch of brass I decided to clean was some well-weathered 5.56mm brass I picked up at the range. I was really interested to see how this rifle brass turned out. It would be really nice if the insides were as clean as the pistol brass. A clean interior neck would most likely aid in accuracy. I love the way it feels to slide a bullet into a new piece of brass! As you can see this brass is heavily weathered. I did not do anything special to clean it either. I simply put it in the tumbler, filled it with water, added soap, added Lemi-shine, and tumbled it for four hours. The outcome is basically new brass — the brass is totally clean, inside and out.



Here are some photos of another batch of military 5.56 brass, this time once-fired Lake City brass. The Lake City brass is shown, prior to cleaning, in a zip-lock bag. The next two shots show this LC brass after cleaning. Pretty impressive — even the primer pockets are clean.




After STM cleaning, this once-fired Lake City brass looks like new Lake City to me. Here are close-ups of the case mouths and the primer pockets.

Thoughts and Conclusion
Many of you will think the system is a little expensive ($230.00 for Thumler's Tumbler and Stainless Media), so it will be difficult to recoup your investment. That is not a good reason for using sub-par equipment in my opinion. I don't reload because of the money savings. You will never save money reloading anyway. By the time you factor in your time, equipment, and consumables, you should just buy new ammo. editor's note: Have to disagree here. With some cartridges, factory ammo costs 2 to 3 times as much as handloads, IF match-grade ammo is available at all. Also, you need consider how the STM system would be amortized over thousands of reload cycles. The stainless pins last forever — they never wear out. If you clean and reload 500 cases ten times, the cost of tumbling with the STM system (not counting electricity and water) is less than five cents per round.

I reload because it is fun. I like to make my own bullets. I like to tailor them to certain tasks and make them the best I can. It's like man-knitting for me. In the end, instead of a sweater, I have a big pile of shiny bullets I can go shoot. And I like shiny, clean brass. So from that perspective, the rotary tumbler filled with stainless media is a welcome addition to my bench. The Stainless Tumbling Media system is fantastic. Give it a try, you won't be disappointed!