For many years I’ve been using Dave Maurer’s 4mm x 5mm angle-cut ceramic media to clean .40-65 & .45-70 BPCR cases in a Tumbler’s Model B tumbler. It’s always worked great. I also have a relatively large ultrasonic cleaner (holds 1.3 gallons of liquid) with an internal heater and wondered how well it would work for case cleaning. And more recently, after reading several reports, I decided to try stainless steel pin media in the tumbler.
Ultrasonic versus Tumbler with Ceramic Media Always wondering which method was the best solution for cleaning BPCR brass, I split up a batch of 200 pieces of very dirty brass. They were fired with black powder and allowed to set without cleaning and with primers still in place for well over two years. The brass was included with a rifle I purchased for resale. I will not cover the details of the test here but, from a speed and cleaning perspective an ultrasonic cleaner is by far the fastest technique. If the primers are removed and the cases tossed in a soaking solution shortly after firing, a good ultrasonic cleaner will finish the job in a few minutes. Also, the ultrasonic cleaner was much faster when removing the brass. Just lift up the wire basket and dump the brass in a bucket or bowl of hot clean water to remove any remaining cleaning solution residue. But a good large ultrasonic cleaner is significantly more expensive, several hundred bucks more, than a good tumbler and ceramic media. Another benefit of ultrasonic cleaning is there are no limitations to case size or configuration. It will work just as well on bottleneck or very small cases.
The cheaper tumbler and ceramic media approach does require more run-time but will eventually accomplish the same level of cleaning for larger cases, and it excels in improving the appearance of the outside of the brass. To separate the brass and ceramic media does require tapping and checking the inside of each case to ensure no media is stuck inside. A tumbler and ceramic media is not recommended for bottleneck cases and may not be a good solution for smaller cases unless smaller ceramic media is used.
Cleaning cases with ceramic media can slightly shorten the case due to burnishing (peening) of the lip edge and roll over the lip edge. When case lengths are trimmed during the case preparation and reloading process, a chamfering or deburring tool is typically used to remove metal burrs or whiskers from inside and outside of the case lip. Excessive chamfering will thin the case lip which the ceramic media can easily burnish (wear down) or bend over.
Tumbler with Stainless Steel Pins I’ve been using ceramic media to clean .40-65 and .45-70 BPCR cases. The cases came out shinny and spotless. The insides were clean as were the primer pockets. So I was a happy shooter until I acquired a .38-55 Win. rifle along with a couple hundred dirty cases. Reports on shooting forums suggested that the ceramic media I was using may not work as well in smaller diameter cases. Sure enough, after running the cases in the tumbler for a few hours, the primer pockets and outside looked great, but the condition of the inside walls left a lot to be desired, especially deep inside next to the primer hole. Also, there were some problems with the ceramic media wedging inside a few cases. So a decision was necessary if I intended to forego using my ultrasonic cleaner and use the tumbler; look around for a source of smaller ceramic media or give stainless steel (SS) cut wire pins a try. By the way, Dave Maurer also supplies ceramic media in smaller sizes (3mm x 5mm), reported to work well in smaller cases.
Based on feedback posted on several forums, I decided to try SS pins. SS pins are very small in diameter, will easily clean the smallest crevices and slide through primer holes without jamming up. Since I also reload and shoot several smokeless handgun and bottleneck rifle calibers there were additional reasons to try SS pins. If they work well for cases as small as .380 Auto than I’d have a one-size-fits-all calibers-and-case solution. But the results proved less than satisfactory for large BPCR cases.
SS media pins are available in 5 lb bags from several shooting supply retailers such as Midway, Brownells and Buffalo Arms. A 5 lb bag is ideal for use in the Tumbler’s Model B tumbler. Smaller 1 lb bags are also available, mainly to replace the media lost during cleaning and handling, more on this later. I picked up a 5 lb bag of Pellets LLC brand from MidwayUSA. Prior to discussing the cleaning results, I should share some of the information found while researching the subject.
Most folks are under the impression that stainless steel is nonmagnetic, which is not necessarily the case. Without going into a lot of detail on the subject, there are different types of SS alloys. The composition of the alloy, the manufacturing process and the resulting crystalline structure determines the magnetic properties. Generally, when the alloy contains a significant amount of nickel, the resulting crystalline structures are less magnetic. If manganese is used rather than nickel, the austenitic crystalline structure is more magnetic and the SS is cheaper to make. Pellets LLC’s brand of SS pins are magnetic. I understand the SS pins from Brownells and Buffalo Arms are also magnetic. Due to the size, being magnetic has advantages.
The Pellets LLC brand pin dimensions are approximately 0.250” long and 0.040” in diameter, not much larger in diameter than a sewing machine needle, but much shorter. They’re small enough that I actually found a few attached to small bubbles and floating on the water surface. The surface tension and air bubbles were sufficient to keep some of the tiny pins from sinking, similar to the property that allows small insects such as water striders to walk on water. Here’s where the magnetic properties are an advantage. It provides a way to pick up spilled pins. There is no way that you will clean a bunch of brass and separate the media without dropping or spilling a few pins. And you will be in “deep doo-doo” if you drop a few on the carpeted floor and the wife of kids step on them. My office and loading room (converted bedroom) has carpeted floors, and a strong magnet did a great job of picking up a few I spilled. So how well does the pins work?
With the 5 lbs of pins in the tumbler, lots of water and an ounce of Dave Maurer brass cleaning concentrate, various handgun and bottleneck cases were cleaned. They all came out looking brand new, inside and out with completely cleaned primer pockets. Here are a couple of YouTube videos that provide a visual detail of the process: https://www.youtube.com/watch?v=wUItmkwdeL0 https://www.youtube.com/watch?v=i-6SOiWE8Hc At this point I was completely “sold” on SS pins, but later uncovered a significant problem when cleaning larger BPCR cases.
Case Lip Peening After cleaning a batch of .40-65 cases with the tumbler and SS pins, it became clear that the lip or edge of the case mouths were expanding (flaring out and rolling over in both directions, but mostly to the inside) as much as 0.004” wider than normal due to a peening effect which I had not noticed earlier when cleaning the handgun cases. And peening had never been a problem when using ceramic media in the tumbler – more on this later. To determine if the water level in the tumbler was a factor affecting the amount of agitation and the rate of peening, a short experiment was conducted with two batches of 25 new .45-70 cases. One test batch was with the water level only covering the pins (low-water test). The 2nd test batch was with the tumbler filled with water to within 1” of the top. The case lips were peened in both tests, but to a lesser degree with the tumbler almost full. Note: Closely inspecting the previously cleaned handgun cases indicated the lips were peened which I had overlooked at the time.
After reporting the test results on a couple of BPCR discussions forums, some shooters responded that the peening was due to using stainless pins with Thumler’s high speed 3,000 rpm motor, the motor installed on my tumbler. The slow speed (1,550 rpm) motor was recommended to eliminate peening.
The slow speed motor was ordered and installed and the worse-case low-water test was repeated. It quickly became clear that peening was not eliminated but was significantly reduced. Further testing indicated the slow speed motor resulted in less drum noise and required more run time to clean cases, neither of which was a surprise.
Later, I ran the same tests as above but with 7 lbs of Dave's Maurer's large ceramic media with 50 .40-65 Rem. cases in a Thumler's Model B with the hi- speed 3000 rpm motor. Several case lip thicknesses were measured with the measurement locations identified. Measurements were taken at 2 hr increments over 6 hrs. The drum was filled with water to just over the media and brass, so the drum was a little over half full. No measurable peening was detected, but read on.
Sometime later, after annealing the case necks, peening was evident with ceramic media. Annealing apparently softens the necks sufficiently for peening to result even if using ceramic media. Following the purchase of a very nice annealing machine I now anneal cases prior to every reloading and have noted an increased rate of case lip peening, but believe the benefits of annealing are greater than the negatives associated with lip peening.
Due to additional testing there’s no question in my mind that peening is definitely due to rotary tumbling. And the rate of peening is determined by several factors: brass softness, rotational speed of the tumbler, type of media, how full the tumbler is loaded, how long the dirty brass was soaked prior to tumbling and finally the tumbler run time. If someone tumbling brass with ceramic or stainless media does not believe peening is taking place than they have not measured the lip width close enough before and after removing the brass from the tumble. The slight rolled over edge may not be sufficient to cause a problem or shorten the cases appreciably, but one cannot tumble brass with ceramic or stainless media without some peening taking place.
Dave Maurer, the supplier of ceramic media to many shooters, suggests using tennis balls in the tumbler to eliminate peened lip edges. He says to fill the tumbler full of tennis balls after putting in the media and brass. The tennis balls prevent the brass and media from falling far enough in the tumbling process to peen. Some have suggested that peening will not happen if the tumbler is filled to the top with water while others say to only add enough water to cover the media prior to adding the dirty brass.
As noted earlier, at one point in time I concluded from testing that stainless pins caused peening and ceramic media did not, but have since proven to myself that was an incorrect conclusion. The rate of peening can be significantly reduced using some of the techniques mentioned above but it will not be completely eliminated when using a tumbler. To date I have “played around” with all the variables including switching back and forth between ceramic and stainless, purchased a slow speed motor for my Thumler’s; adjusted the tumbler liquid levels, media levels & brass levels; adjusted the frequency of annealing and paid close attention to run time. I tried Dave Maurer’s suggestion of using tennis balls and even tumbled only brass (no media) in plain water and was able to measure peening. As the case lips bang against the media and other cases, lip edge peening is unavoidable. The result is I have proven to myself beyond a shadow of doubt that I can control the rate of peening but it is inescapable, i.e. peening cannot be completely eliminated when using a rotating tumbler. The only methods I know of to eliminate peening is to use an ultrasonic cleaner or a vibrating-style tumbler. Note - For details on techniques to remove the peened edge see the article titled, REMOVING CASE PEENED LIP EDGE.
By the way, regardless of the cleaning technique used, there are at least a couple of ways to quickly dry the wet cases. I’ve tried the towel and hair dryer technique, but prefer standing up the cases in a large frying pan and heating them on the stove top. Turning off the heat when the water vaporizes ensures the temperature is well below the range that will damage the brass or result in discoloration. If you’re in a rush, just aim a small fan at the pan and they will be ready to handle in a few minutes. The same technique can be used for the SS pins if you prefer not leaving them wet when stored in the tumbler drum. Attempting to dry ceramic media using the same technique will work but will take a lot longer since ceramic is a poor conductor of heat. Since I’m usually cleaning brass at least once a month I just store the wet ceramic media in the tumbler drum until it’s needed.