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Ultrasonic Case Cleaning

By Brownells Staff

Ultrasonic cleaning rose into prominence about 15 to 20 years ago when new government regulations severely restricted the use of chlorofluorocarbons. These solvents were widely used as cleaning agents in most industries involved with metal. Industries soon found that ultrasonic cleaning was more effective at degreasing/cleaning, faster, cheaper, and environmentally friendly. A light bulb went off in the heads of competitive shooters who are always looking for an “edge”. Long-range and competitive shooting have become so technical and complex that any improvement in your technique has the potential to increase your winning ability. These shooters spend more time in case preparation than any other aspect of shooting. Ultrasonic case cleaning would seem to be the perfect addition to a shooter’s repertoire. Perfection can only be achieved if your cases are methodically and meticulously prepared. Uniform cases and loads mean low standard deviations, which translate into smaller groups.

As you are aware, every time a case is fired, it leaves behind tough and stubborn deposits inside the case and primer pocket. With time, you will notice that the carbon and powder residues inside the cases will begin to flake off when you are processing your brass. Although, it is not known what affect, if any, this residue has on your finished load, a completely clean case is your ultimate goal. A case that becomes ultra clean exactly duplicates the conditions found in new brass, which most shooters use to develop their loads.

The long standing tradition of case cleaning involves the use of a case tumbler and treated corn cob or walnut shell media. Unfortunately, a case tumbler is only able to clean the outside of the case and doesn’t remove any residue inside the case or the primer pocket. Another downside to case tumbling is that it is fairly common for the media to become lodged in the case and flash hole and it is imperative that it be removed. In addition, case tumbling takes far longer and accomplishes considerably less than ultrasonic cleaning. Although ultrasonic cleaners are more costly, their numerous benefits make them cost effective for the professional or casual shooter.

Ultrasonic cleaning uses high-frequency sound waves (generally between 20-80 kHz) to remove a variety of contaminants from objects immersed in a liquid. The result of these high-frequency sound waves is a process called cavitation. These high frequency bursts of ultrasonic energy produce a three-dimensional wave of alternating positive and negative pressure areas as the sound wave passes through the solution. During negative pressure, microscopic cavitation bubbles form and will continue to grown until they reach resonant size. As the positive sound wave passes, the pressure rises rapidly and implodes these tiny bubbles. Before these miniscule bubbles implode they store a tremendous amount of energy. These bubbles can be as hot as 10,000 degrees and have as much as 50,000 lbs per square inch of pressure. This sounds alarming, but you have to remember that these bubbles are microscopic in nature and pose no harm to anything, unless you are a carbon /powder residue deposit on a cartridge case! When this cavitation bubble implodes near your brass case, it transforms the bubble into a jet about 1/10th of its size. This jet of energy can travel as fast as 400 km/hour. At 43 kHz, as is the frequency for our L & R HCS 200 ultrasonic cleaner, this is happening 43,000 times per second. This micro-burst of extreme energy is responsible for removing contaminants from the surface of your cartridge brass. Ultrasonic cleaning can reach into crevices and inaccessible areas and remove surface debris that can’t be cleaned by any other process.

The purpose of this experiment was to test the effectiveness of an ultrasonic cleaner at removing carbon/powder residues from the inside and outside of the cartridge case, as well as the primer pocket. I chose the L & R HCS 200 Ultrasonic Cleaning System (# 515-000-006) because its size is perfect for cleaning brass and it is affordable.
Ultrasonic Handgun Cleaning System

In addition to using the cleaning solution supplied with this kit, I wanted to test the effectiveness of the M-Pro 7 gun cleaner (#945-700-128). I have been hearing good things about their products, and since they stated that it could be used as a tank solvent I wanted to give it a try. I also wanted to compare how a conventional case tumbler cleans to the ultrasonic cleaning system.

I will be using two different sizes of cases to compare the effectiveness of ultrasonic cleaning. The first case I will be testing is a Tactical Twenty round. I am using IMI .223 SS 109 brass (small rifle primer) necked down to .20 caliber.

It is logical to assume that a case with a smaller case mouth and smaller primer pocket will require a longer time for the ultrasonic cleaner to work. I will test both once fired brass as well as those that have been fired for five consecutive times. The rifle that I used is a Tromix custom-built AR-15. Ar-15s are hard on brass and tend to leave the exterior case necks much “dirtier” than one would find with a bolt action. The second larger case that was evaluated was the 260 Remington. The 260 has a 6.5mm case mouth and also utilizes a large rifle primer. These cases were once-fired from a DPMS LR-260, an AR-10 platform. The larger 260 Remington case should prove to be an easier case to clean.


260 Remington cases after cleaning.
Left to Right: Tumbled, HCS 200, & M-Pro 7

The setup of the HCS 200 ultrasonic cleaning system is quick, extremely easy, and uncomplicated. The ultrasonic cleaning system can be broken down into three simple steps:

  1. Immersion of cartridge cases into an aqueous solution in an ultrasonic tank until clean.
  2. Rinse cases in distilled water to remove any detergent residues. The use of distilled water is very important because using tap water can introduce mineral impurities which can possibly cause oxidation of the brass.
  3. Dry the cases to prevent oxidation of the brass. This process can occur naturally by allowing to dry overnight on a towel or can be speeded up by using a heat source such as a hair dryer.

The HCS 200 ultrasonic cleaning system housing is rectangular (6 3/4” X 12 ½”) in shape and the only component visible is a stainless tank that the cleaning solution is placed in. It has a capacity of 4 7/8 th quarts. The cases are placed in a single layer (manufacturer’s recommendation) on the bottom of the supplied stainless steel mesh basket.

The basket has a handle on each side that when placed in the tank is supported by the tank wall. There is an indentation inside the stainless tank at each corner that shows at what level to fill the cleaning solution to. There is also a lid which covers the tank when it is running. The HCS 200 also has a lubricating tank (same size as the above) which I use for immersing the cases in distilled water. Simply plug the ultrasonic cleaner into a 110 volt electrical outlet and push your on button and your cases start to clean. Note: Before beginning to clean cases, the cleaning solution must be degassed. The degassing process simply removes entrapped air from your cleaning solution. This air can greatly reduce your ultrasonic cleaning action. This process normally takes only 10-20 minutes. Although not absolutely necessary, if you don’t, it will take longer the first time your brass are cleaned with the new solution.

When you are finished cleaning your cases make sure that you remove the cleaning solution from the tank and store it in an appropriate container. I found that a one-gallon Tupperware with a re-closable spout works great. Do not use flimsy plastic water or milk jugs. When emptying your cleaning solution out of your tank make sure that you filter it. You will see that the bottom of the tank is filled with the contaminants that were removed from your cases. To filter I use a large automotive-type funnel and a large filter used for filtering frying oil. These can be found at any place that sells turkey frying equipment. You could also use several layers of cheese cloth as a filter. By taking care of your cleaning solution you will be able to use it multiple times. Since the ultrasonic cleaner seems to work better with warmer cleaning solutions, I like to heat it up in a microwave until the temperature is in the range of 100-1200Fh. Although this is not an absolute, a solution that is cold definitely increases cleaning time.

HCS 200 Cleaning Solution Test
Once-Fired Tactical Twenty Cases
Mix 8 oz jar of HCS 200 cleaning solution (two 8 oz jars supplied) with enough warm water to fill the tank to the designated level (notch in each corner of the tank). Degas the solution for 15 minutes. The stainless steel mesh basket held 63 Tactical Twenty cases placed in a single layer. The temperature of the starting solution was 102 0Fh. When the cases were removed the temperature was 110 0Fh.

Time
Observations
5 minutes
The exterior of the cases are not significantly brighter/cleaner. The primer pockets and case interiors are still dirty.
10 minutes
Exterior of the cases are brighter. 70% of the cases show some degree of cleaning of the primer pockets. Little difference seen inside the case, but case mouths are cleaner.
15 minutes
Case brightness is about the same. Still only 70% of the primer pockets are clean, but a larger portion of each is cleaner. A Q-tip swabbed inside the cases shows that carbon/powder residues are loosening up.
20 minutes
Case exteriors are brightening up. 80-85% of the primer pockets are about 90% clean. The insides of the cases and case mouths are cleaner.
25 minutes
Cases are brighter/cleaner than even new brass. 80-85% of the cases have almost completely clean primer pockets. The inside of the cases are 80-90% clean.
30 minutes
The insides of the cases and case mouths appear to be completely clean. 87% of the primer pockets are virtually 100% clean. 13% of the cases had stubborn primer pocket residue that could not be completely removed.
60 minutes
Eight cases (13%) were placed in the tank for another 30 minutes to try to remove the remaining residue in their primer pockets. Six out of the eight cases were completely clean.


Five-Time Fired Tactical Twenty Cases

Time
Observations
30 minutes
Based on the above observations, I didn’t begin to observe these 5-time fired cases until after 30 minutes. The exterior cases are bright/clean. Brighter than new cases. The primer pockets on 75% of the cases are 75% clean. The remaining cases had primer pockets that were only 25% clean. The inside of the cases appear to be clean.
65 minutes
25% of the primer pockets were 95% clean, 25% of the primer pockets were 90% clean, 25% of the primer pockets were 85% clean; and 25% were 80% clean.
75 minutes
75% of the primer pockets were 90% clean.

Once-Fired 260 Remington Cases
A single layer of 40 once-fired 260 Remington cases (Remington brand) were placed in the basket and immersed in the cleaning solution.

Time
Observations
5 minutes
60% of the cases had primer pockets that were at least 50% clean. The outside cases are significantly brighter/cleaner. A minimum of 50% of the case insides are clean.
10 minutes
70% of the brass had at least 50% of the primer pockets clean. Most of the case insides are clean except at the case heads.
15 minutes
90% of the primer pockets are 75%-100% clean. The inside of the cases appear to be totally clean except near the case heads.
20 minutes
Primer pockets are about the same. 50-60% of the cases are clean on the inside near the case heads.
25 minutes
About 75% of the inside case heads are now clean.
30 minutes
No significant changes from 25 minutes.
35 minutes
No significant changes from 30 minutes.
45 minutes
No change in primer pockets. 90% of the cases are clean inside the cases at the case heads.
55 minutes
Little change was noticed and test was suspended.


M-Pro 7 Cleaning Solution Test
Once-Fired Tactical Twenty Cases
Since the M-Pro 7 cleaning solution was new, it needed to be degassed for 15 minutes. The starting temperature of the M-Pro 7 was 80 0Fh and 90 0Fh after degassing. A single layer of 63 Tactical Twenty cases were immersed.

Time
Observations
5 minutes
Exterior of cases are somewhat brighter.
10 minutes
Exterior of cases brighter/cleaner. Inside of case necks are beginning to become clean. Primer pockets are still dirty, but residue is starting to loosen up.
15 minutes
Case exteriors are even brighter. Inside of cases are cleaner.
20 minutes
The exterior case necks are about 75% clean. Inside case necks were also cleaner. The powder residues on the inside are much looser and are easily removed by swabbing a Q-tip.
25 minutes
Exterior cases are still brighter/cleaner. Outside case necks are completely clean. Case insides are cleaner.
30 minutes
Most primer pockets are 50-75% clean.
35 minutes
Inside cases appear to be clean.
40 minutes
90% of the primer pockets are clean.
45 minutes
No change.
50 minutes
No change.
55 minutes
No change and test was suspended.

Five-Time Fired Tactical Twenty Cases

Time
Observations
30 minutes
Based on the above results, I didn’t start making observations until 30 minutes. 25% of the cases had primer pockets 50% clean. 75% of cases had primer pockets 10% clean. 80% of the inside cases are clean except around the case heads.
40 minutes
25% of the cases had primer pockets 100% clean. 75% had no change. Most cases were clean inside even around the case head. No other changes were observed until 70 minutes.
70 minutes
The remaining 75% of the cases had 80% clean primer pockets. Test suspended.

Once-Fired 260 Remington Cases

Time
Observations
5 minutes
30% of the cases had primer pockets 50% clean. 30% of the cases had 75% of the case insides clean.
10 minutes
30% had primer pockets 75% clean. 40% had 50% clean. 20% had 25% clean pockets and 10% had only 10% of the primer pockets clean. Case exteriors are bright and shiny.
15 minutes
Primer pockets the same. 60% of the cases were almost 100% clean inside even near the case head.
20 minutes
30% of cases had 90% clean primer pockets, 20% had 80% of the pockets clean, 40% had 50% of the pockets clean, and 10% had 30% of the primer pockets clean. 80% of the cases are 90-100% clean inside. 20% are 70-80% clean inside.
25 minutes
40% of the cases with 90% clean primer pockets, 20% of cases with 80% of pockets clean, 30% of cases with 60% of pockets clean, and 10% of the cases with 50% of the primer pockets clean
30 minutes
Cases are the same.
35 minutes
60% of the cases had 90-100% of the primer pockets clean, 10% of the case with 80% of pockets clean, 10% of cases with 70% of the primers clean, and 20% of the cases with 40% of the primer pockets clean.
45 minutes
Cases are the same.
55 minutes
18% of the cases have 100% of the primer pockets clean, 30% have 90% of the pockets clean, 30% have 80% of the pockets clean and 22% had 70% of the primer pockets clean. Test suspended.

Primer Seating Test
Tactical Twenty Cases
Some people who have been cleaning cartridge cases ultrasonically have stated that the cases are so clean that it makes it difficult to seat primers. I wanted to put this statement to the test by priming 10 Tac Twenty cases that have been cleaned in a tumbler and then had primer pockets cleaned with a Sinclair primer pocket uniformer, 10 cleaned by HCS 200 cleaning solution, and 10 cleaned with M-Pro 7 cleaner. CCI 450 small rifle magnum primers were used. A Lee Auto-prime tool was used because of its ultra-sensitive feel when seating primers.

Treatment

Amount of Seating Force Needed to Seat Primer

Easy

Moderate

Tumbled & Primer Pocket Cleaned

30%

70%

HCS 200 cleaner

70%

30%

M-Pro 7 cleaner

50%

50%

260 Remington Cases
The above test was repeated with 260 Remington cases. CCI BR-2 large rifle benchrest primers were used in this test. 10 cases were tumbled and primer pockets cleaned with a Sinclair primer pocket uniformer, 10 cases cleaned with HCS 200 cleaner, and 10 with M-Pro 7.

Treatment

Amount of Seating Force Needed to Seat Primer

Easy

Moderate

Tumbled & Primer Pocket Cleaned

30%

70%

HCS 200 cleaner

60%

40%

M-Pro 7 cleaner

50%

50%

Results
Cases Tumbled
In separate batches, Tactical Twenty and 260 Remington cases were tumbled in treated walnut shell media for over an hour. Walnut media was used because of its more aggressive cleaning action when compared to corn cob media. As expected, the outside of the cases were nice and shiny, but that was the extent of improvements. Also, a tumbler is very noisy and needs to be placed far away from you, preferably outside. Whereas, an ultrasonic cleaner is so quiet that you can sit next to it and hardly know it is on. A case tumbler basically serves as a case polisher and nothing else. Of course, you also have the tedious extra work of separating the cases from the media. Then you must make sure that all the media has been dislodged from inside the cases, especially the flash holes. Definitely not the best “Bang for the Buck”.


HCS 200 Cleaned Cases
The cleaning solution that was supplied with the HCS 200 ultrasonic cleaning system achieved excellent results at a minimum cost. Based on observations with once-fired small sub-caliber cases, 30 minutes seems to be an adequate amount of time to clean the cases. 87% of the cases were bright/shiny on the outside and sparkling clean on the inside. In fact, new cases do not look as good as cases cleaned in an ultrasonic cleaner. An additional 30 minutes was required to clean approximately 9% more cases. Instead, I would merely clean the remaining dirty primer pockets with a Sinclair primer pocket uniformer.

Tactical Twenty cases that were fired five-times needed extra time to achieve the same results. After 30 minutes, only 75% of the cases had primer pockets that were 75% clean. The inside of the cases did appear to be clean at this point. After an additional 45 minutes of ultrasonic cleaning 75% of the cases were now 90% clean. Once again, it would be quicker and more efficient to manually clean the primer pockets. This demonstrates why you should ultrasonically clean your brass after each firing.

After only 5 minutes of cleaning, the large once-fired 260 Remington cases with their larger primer pockets were already starting to clean. The exterior of the cases were already significantly brighter/cleaner. By 15 minutes 90% of the primer pockets were 75% clean and the inside of the cases (except near the case heads) appeared to be completely clean. Based on our results, larger cases should probably be clean within 20-25 minutes. This time frame is only an approximation since several factors could influence the final outcome. Type and brand of primer could be a factor in how easy or difficult a primer pocket is to clean. As most reloaders are aware, there are some powders that burn extremely clean and others who leave a considerable amount of residue behind. Plus, you have slow, medium, and fast burning powders. In addition, the composition of powders can vary considerably. I am sure all these factors and more contribute to how easy or how stubborn case residue is to remove.

M-Pro 7 Cleaned Cases
I noticed initially that M-Pro 7 brightened and cleaned up the outside of the Tactical Twenty cases faster than HCS 200. After 30 minutes though, M-Pro 7 was only slightly brighter than HCS 200. M-Pro 7, while it did a good job of cleaning, took longer than the HCS 200 cleaning solution. On average, M-Pro 7 takes about 10-15 minutes longer to accomplish the same level of cleanliness as that of HCS 200. This principle applied to both once-fired and five-time fired Tactical Twenty brass. The once-fired 260 Remington brass also took 10-15 minutes longer to clean with M-Pro 7. This may be attributed to the fact that M-Pro 7 is a cleaner and a lubricator, while HCS 200 is only a cleaning solution. The added attribute of lubrication may be well worth the extra time needed to clean cases.

Primer Seating Test
The results of our primer seating tests with Tactical Twenty and 260 Remington brass was just the opposite of what others have reported. I found that the ultrasonically cleaned brass, both HCS 200 and M-Pro 7, were significantly easier to prime and with considerably less force involved. In addition, I found that cases that had some primer pocket residue remaining did not seat any different than those that were perfectly clean. I believe that this is due to the fact that only an ultra-thin layer of residue remains and therefore it is not enough to interfere with primer seating. Of course, if you are a perfectionist like me, go ahead and get out your primer pocket cleaner.

I suspect that some of the problems seen by others were due to the various non-conventional cleaning solutions that they employed. Most of these home-made solutions contained household vinegar which was acidic in nature. L&R, the manufacturer of the HCS 200 cleaning solution, states that it contains no acid and will not harm cartridge cases. The problem with using these concoctions is that you have no idea how they will react and what they will do to your brass. Unless you are a trained chemist/metallurgist, I suggest that you use only solutions approved for ultrasonic cleaning. The possible risk involved is not worth saving a few pennies!

As I stated previously, I am a perfectionist and take great pride in the preparation of my cartridge cases. I go to great lengths to make sure that I have accurately done everything that I need to do and will have used every gadget known to man to accomplish this goal. Unfortunately, after all is said and done, the cases still look like used cases. After enduring the nerve-wrecking sounds of the case tumbler, the brass still didn’t quite measure up to the squeaky-clean look and feel of new pristine brass. Primer pockets can be easily cleaned, but how do I revert the inside of the case back into looking new. The HCS 200 Ultrasonic Cleaning System (#515-000-006) greatly exceeded my expectations. Now, all my cases look even better than new, inside and out, within a relatively short period of time. All this is accomplished with little effort on my part. I can clean my cases and still have peace of mind. The HCS 200 cleaning system is so affordable that any shooter, at any level, can justify its purchase. This is one “gadget” that I can’t do without and neither can you!