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January 13th, 2023

Ultrasonic Case Cleaning — Determining the Optimal Dwell Time

cartridge brass case ultrasonic liquid cleaning dwell time brownells

If you read our lengthy article on Ultrasonic Case Cleaning by Jason Baney, you’ve seen the remarkable results that can be achieved with this method, as shown by the photo above. Ultrasonic cleaning has many advantages over traditional tumbling methods of case cleaning. There is no dust or media residue to remove from the brass, and when done right, the cases come out clean and shiny, inside and out, even the primer pockets.

In its Benchtalk Archives, Brownell’s has an excellent article discussing Ultrasonic Case Cleaning. Brownell’s staff compares results, with measured dwell times from 5 to 75 minutes, using both Mpro-7 and HCS 200 cleaning solutions. Tests are performed with once-fired and 5X-fired Tactical 20 (Tac20) cases, as well as once-fired .260 Rem Cases. The article also compares the results from ultrasonic cleaning vs. tumbling in walnut media. Below are Brownell’s results for Tac20 cases with the HCS 200 (non-acidic solution). Go to Brownell’s article for MPro7 results and Rem 260 results.

HCS 200 Cleaning Solution Test

Procedure — Solution was de-gassed for 15 minutes, then 63 Tac20 cases were placed in a single layer, in stainless steel mesh basket. The temperature of the starting solution was 102° F. When the cases were removed the temperature was 110° F.

Once-Fired Tactical Twenty Cases (HCS 200) — 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-Times Fired Tac20 Cases — 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.

How Does Ultrasonic Cleaning Work?
The Brownell’s Benchtalk article explains: “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 minuscule 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.”

Photos and quotes © Brownells®, Inc. All Rights Reserved, Used with Permission.

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip No Comments »
September 16th, 2022

Get Smart — Access AccurateShooter.com’s Tech Articles Archive

AccurateShooter.com technical articles

AccurateShooter.comReaders who have just recently discovered the Daily Bulletin may not realize that AccurateShooter.com has hundreds of reference articles in our archives. These authoritative articles are divided into multiple categories, so you can easily view stories by topic (such as competition, tactical, rimfire, optics, shooting skills etc.). One of the most popular categories is our Technical Articles Collection. On a handy index page (with thumbnails for every story), you’ll find over 120 articles covering technical and gunsmithing topics. These articles can help you with major projects (such as stock painting), and they can also help you build more accurate ammo. Here are six popular selections from our Technical Articles archive.

pillar Bedding

Stress-Free Pillar Bedding. Richard Franklin explains how to do a top-quality bedding job, start to finish.

Gun Safe Technical Buyers Guide

Gun Safe Buyers Guide. Our comprehensive Safe Buyers Guide examines the key features to consider in a safe — Wall Thickness, Volume, Shelving, Fire Rating, Lighting, Weight and more. We also explain the Pros/Cons of Dial vs. Digital (Keypad) locking systems.

Savage Action Tuning Torque Settings

Savage Action Tuning. Top F-TR shooter Stan Pate explains how to enhance the performance of your Savage rifle by optimizing the torque settings of the action screws.

Precision Case Prep for Reloading

Complete Precision Case Prep. Jake Gottfredson covers the complete case prep process, including brass weight sorting, case trimming, primer pocket uniforming, neck-sizing, and, case-neck turning.

rifle stock painting and spraying

Stock Painting Instructions. Step-by-step guide for stock painting by expert Mike Ricklefs. Mike shows both simple coverage and fancy effects.

Ultrasound ultrasonic CAse Cleaning

Ultrasonic Case Cleaning. This article reviews the recommended process for cleaning cartridge brass with ultrasonic cleaning machine. We cover the right liquid solutions, processing times, and case drying options.

Permalink - Articles, Bullets, Brass, Ammo, Reloading, Tech Tip No Comments »
July 22nd, 2022

Clean Brass Effectively with Ultrasonic Cleaning Machines

Ultrasonic Cleaning RCBS Ultrasound .308 Winchester 7.62x51 brass casings

Tumblers and walnut/corncob media are old school. These days many shooters prefer processing brass rapidly with an ultrasonic cleaning machine. When used with the proper solution, a good ultrasonic cleaning machine can quickly remove remove dust, carbon, oil, and powder residue from your cartridge brass. The ultrasonic process will clean the inside of the cases, and even the primer pockets. Tumbling works well too, but for really dirty brass, ultrasonic cleaning may be a wise choice.

READ FULL UltimateReloader.com Article on Ultrasonic Case Cleaning »

Our friend Gavin Gear has evaluated an RCBS Ultrasonic cleaning machine using RCBS Ultrasonic Case Cleaning Solution (RCBS #87058). To provide a real challenge, Gavin used some very dull and greasy milsurp brass: “I bought a huge lot of military once-fired 7.52x51mm brass (fired in a machine gun) that I’ve been slowly prepping for my DPMS LR-308B AR-10 style rifle. Some of this brass was fully prepped (sized/de-primed, trimmed, case mouths chamfered, primer pockets reamed) but it was gunked up with lube and looking dingy.”

UltimateReloader.com Case Cleaning Video (7.5 minutes):

Gavin describes the cleaning exercise step-by-step on UltimateReloader.com. Read Gavin’s Cartridge Cleaning Article to learn how he mixed the solution, activated the heater, and cycled the machine for 30 minutes. As you can see in the video above, the results were impressive. If you have never cleaned brass with ultrasound before, you should definitely watch Gavin’s 7.5-minute video — it provides many useful tips and shows the cleaning operation in progress from start to finish.

Ultra Dry Necks After Ultrasonic Cleaning — Some Suggestions
The Ultrasonic cleaning process gets cartridge brass so “squeaky clean” that increased force may be required to seat your bullets, or they may “grab” as they go in the necks. To reduce bullet-seating effort, you may benefit from adding a little dry case lube inside the case-neck before loading (use a nylon brush). Another trick is adding a teaspoon of Ballistol lube to the cleaning solution. That provides a trace lubricant inside the necks, but does not interfere with powder ignition in any way.


The latest Gen2 RCBS ultrasonic cleaning machine has a large 6.3-quart capacity. That’s nearly 100% larger than the first generation machine in Gavin’s video. The Gen2 machine, $406.99 on Amazon, features a second ceramic heater and transducer to better clean brass cases and firearm parts. The LED is easily programmable, and the timer can be set for up to 30 minutes of cleaning. The original 3.2 quart-capacity RCBS ultrasonic machine, as shown in Gavin’s video, is still available for $180.72 at Midsouth Shooters.

Permalink - Videos, Bullets, Brass, Ammo, Gear Review, Tech Tip No Comments »
January 14th, 2022

Ultrasonic Case Cleaning — What Is the Best Dwell Time?

cartridge brass case ultrasonic liquid cleaning dwell time brownells

If you read our lengthy article on Ultrasonic Cleaning by Jason Baney, you’ve seen the remarkable results that can be achieved with this method, as shown by the photo above. Ultrasonic cleaning has many advantages over traditional tumbling methods of case cleaning. There is no dust or media residue to remove from the brass, and when done right, the cases come out clean and shiny, inside and out, even the primer pockets.

In its Benchtalk Archives, Brownell’s has an excellent article discussing Ultrasonic Case Cleaning. Brownell’s staff compares results, with measured dwell times from 5 to 75 minutes, using both Mpro-7 and HCS 200 cleaning solutions. Tests are performed with once-fired and 5X-fired Tactical 20 (Tac20) cases, as well as once-fired .260 Rem Cases. The article also compares the results from ultrasonic cleaning vs. tumbling in walnut media. Below are Brownell’s results for Tac20 cases with the HCS 200 (non-acidic solution). Go to Brownell’s article for MPro7 results and Rem 260 results.

HCS 200 Cleaning Solution Test

Procedure — Solution was de-gassed for 15 minutes, then 63 Tac20 cases were placed in a single layer, in stainless steel mesh basket. The temperature of the starting solution was 102° F. When the cases were removed the temperature was 110° F.

Once-Fired Tactical Twenty Cases (HCS 200) — 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-Times Fired Tac20 Cases — 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.

How Does Ultrasonic Cleaning Work?
The Brownell’s article explains: “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 minuscule 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.”

Photos and quotes © Brownells®, Inc. All Rights Reserved, Used with Permission.

Permalink - Articles, Bullets, Brass, Ammo, Reloading, Tech Tip No Comments »
July 13th, 2021

Get Brass Ultra-Clean with Ultrasonic Machines

Ultrasonic Cleaning RCBS Ultrasound .308 Winchester 7.62x51 brass casings

Tumblers and walnut/corncob media are old school. These days many shooters prefer processing brass rapidly with an ultrasonic cleaning machine. When used with the proper solution, a good ultrasonic cleaning machine can quickly remove remove dust, carbon, oil, and powder residue from your cartridge brass. The ultrasonic process will clean the inside of the cases, and even the primer pockets. Tumbling works well too, but for really dirty brass, ultrasonic cleaning may be a wise choice.

READ FULL UltimateReloader.com Article on Ultrasonic Case Cleaning »

Our friend Gavin Gear recently put an RCBS Ultrasonic cleaning machine through its paces using RCBS Ultrasonic Case Cleaning Solution (RCBS #87058). To provide a real challenge, Gavin used some very dull and greasy milsurp brass: “I bought a huge lot of military once-fired 7.52x51mm brass (fired in a machine gun) that I’ve been slowly prepping for my DPMS LR-308B AR-10 style rifle. Some of this brass was fully prepped (sized/de-primed, trimmed, case mouths chamfered, primer pockets reamed) but it was gunked up with lube and looking dingy.”

UltimateReloader.com Case Cleaning Video (7.5 minutes):

Gavin describes the cleaning exercise step-by-step on UltimateReloader.com. Read Gavin’s Cartridge Cleaning Article to learn how he mixed the solution, activated the heater, and cycled the machine for 30 minutes. As you can see in the video above, the results were impressive. If you have never cleaned brass with ultrasound before, you should definitely watch Gavin’s 7.5-minute video — it provides many useful tips and shows the cleaning operation in progress from start to finish.

Ultra Dry Necks After Ultrasonic Cleaning — Some Suggestions
The Ultrasonic cleaning process gets cartridge brass so “squeaky clean” that increased force may be required to seat your bullets, or they may “grab” as they go in the necks. To reduce bullet-seating effort, you may benefit from adding a little dry case lube inside the case-neck before loading (use a nylon brush). Another trick is adding a teaspoon of Ballistol lube to the cleaning solution. That provides a trace lubricant inside the necks, but does not interfere with powder ignition in any way.


The latest Gen2 RCBS ultrasonic cleaning machine has a large 6.3-quart capacity. That’s nearly 100% larger than the first generation machine in Gavin’s video. The Gen2 machine, $385.49 on Amazon, features a second ceramic heater and transducer to better clean brass cases and firearm parts. The LED is easily programmable, and the timer can be set for up to 30 minutes of cleaning. The original 3.2 quart-capacity RCBS ultrasonic machine, as shown in Gavin’s video, is still available for $180.72 at Midsouth Shooters.

Permalink - Videos, Bullets, Brass, Ammo, Gear Review, Tech Tip No Comments »