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By Wayne McLerran
Last update: 5/6/16

For several 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, I have
no doubt the ultrasonic cleaner would 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
cleaning solution residue.  But a good larger 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 should work just as well on bottleneck or very small

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
of the lip edge or slightly 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.

By the way, Lyman makes a very nice line of ultrasonic cleaners and specialized
solutions targeted at the firearms and shooters market.  They recently added a
large (6.3 quart) ultrasonic cleaner to their current line.  For more details go to

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
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:
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 (edges 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
- 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
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.

4/7/13 - 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.

Sometime later, afer annealing the case necks, I noticed some peening with
ceramic media but did not run detailed experiments at the time.  Annealing

apparently softened 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.  
More testing will be necessary to
determine the rate of peening with annealed cases.

1/26/15 - Due to additional testing there’s no question in my mind that peening is
definitely due to 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 upon removing the brass from the tumble.  The
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.

At one point in time I concluded from earlier testing that stainless pins caused
peening and ceramic media did not, but have since proven to myself that was an
incorrect conclusion.  You can slow peening down by not annealing or reducing
the frequency of annealing, using a slow speed tumbler motor, using ceramic
rather than stainless pins, completely filling the tumbler, depriming and soaking
the dirty brass and tumbling no longer than necessary, but peening will not be
completely eliminated.

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 level, media level & brass level; adjusted
the frequency of annealing and paid close attention to run time.  In fact, I even
tumbled only brass (no media) for an extended time in plain water and was able to
measure peening.  As the cases drop and the lips bang against 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 tumbler.

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.

Wishing you great shooting,