As a cartridge case is reloaded multiple times, burnt powder residue and carbon builds up on the inside of the case. Unless the case interior is cleaned in some fashion, eventually you’ll see a slight reduction in case capacity. One of our Forum members from Australia wonders about the effects of reduced case capacity: “If the capacity of the case decreases as the crud builds up, then it effectively reduces the size of the cartridge (inside). Wouldn’t that change the pressure produced from that of an equivalent clean case?”
Interesting Test of Case Capacity Changes
Forum member Fred Bohl has actual test results that can help answer the above question. Fred proved that, over a 20-reload cycle, the case capacity of uncleaned cases did decline a small amount. However, surprisingly, this did not seem to affect the actual chronographed velocity of the load. Extreme Spread (ES) did increase, but Fred believes the higher ES was due to changes in case-neck tension, rather than due to the slight reduction in case capacity. Fred reports:
“Back when beginning to use ultrasonic case cleaning, part of the motivation was to get the inside clean based on the assumption that allowing burnt residue to build up inside cases would affect capacity, and, ultimately, performance. An experiment was done to test this hypothesis. The load used, 30.5 grains of RL15 behind 107gr SMKs in a 6mmBR, was selected for best group and lowest ES in prior load development. It turned out to be 92% of initial case capacity and neither “full” or compressed. (I would suspect that different powders, load weight, and total case capacity might produce very different results.)
We took 30 cases of identical initial capacity and tracked three lots of 10 each:
LOT 1: No Internal cleaning LOT 2: Cleaned with media in tumbler LOT 3: Cleaned with Ultrasound machine
Each case (in each lot) was shot and reloaded 20 times. The simplified results after 20 reloads of each lot were as follows:
Lot 1 (not cleaned) – 0.3 to 0.4 gr. loss of capacity, 5 to 8 fps greater ES.
Lot 2 (tumble cleaned) – 0.1 to 0.3 gr. loss of capacity, 4 to 6 fps greater ES.
Lot 3 (ultrasonic cleaned) – no loss of capacity, no detectable change in ES.
FINDINGS
There was no detectable correlation of velocity change to the lots. An oddity was that on very hot days Lot 1 velocities were, occasionally, slightly higher. From results of another ongoing test, I believe the above differences in ES are probably due more to variance in bullet grip tension than case capacity. The ultrasound cleaned cases (LOT 3) did maintain the lowest ES, but we are not 100% sure of the reasons why. More consistent bullet seating might be the reason.”
Editor’s NOTE: Fred’s results do suggest that carbon build-up inside the uncleaned cases might cause a slight increase in pressure that shows up on hot days. Fred has posted that: “A local shooter reported doing the 20 reload, no-clean test on a .308 that gave a loss of capacity of 2.0 grains, doubled ES and significant velocity changes. However, I don’t have any details on his load weight or powder.” Obviously a lot of carbon can build up with 20 reloads. Many shooters retire their brass before then.
Ultrasonic Cleaning and Neck Lube
Some time ago, Jason Baney did a lengthy test on ultrasonic cleaning. Jason found that with his ultrasonically-cleaned cases, the inside of the necks got so “squeaky clean” that he needed to use dry lube in the necks. Jason uses the $21.50 dry lube kit from Neconos.com. This applies ultra-fine Moly powder to the neck using small carbon steel balls.
Many shooters prefer to deprime their brass before resizing. That way they can tumble cases or keep primer debris off their main press. To deprime cases before sizing or cleaning you can use a Decapping Die. This pushes out the spent primer without changing the neck or body of a case. Such decapping dies work fine, but they do require the use of a press. Here is a handy alternative — a cool tool that allows you to deprime brass anywhere — no press needed.
Handheld Primer Removal Tool From Frankford Arsenal
This cleverly-designed Hand Deprimer Tool allows you to deprime cartridge cases without a press. This hand-tool from Frankford Arsenal will deprime brass and capture primers conveniently. You can deprime your cases while watching TV or relaxing in your favorite chair.
This device lets you remove spent primers anywhere — no press needed and all the mess (cups/anvils/residue) stays in the capture chamber. This tool comes works with nearly all common case types up to .338 Lapua Magnum. With good leverage, this tool does the job quickly and efficiently. Forum members have praised this handy tool, but recommend wearing a thick glove if doing more than 100 cases in a session.
How to Adapt Tool for Small Flash Hole Brass
The Frankford Arsenal Deprimer Tool was designed for LARGE flash-hole brass. To deprime brass with small (1.5mm/0.59″) small flash-holes, as found on Lapua .220 Russian and 6mmBR cases, you will need to reduce the pin diameter. Frankford Arsenal currently recommends purchasing a replacement pin and “sanding it down” to the smaller diameter. NOTE: This is NOT difficult — simply spin the stock pin in some sandpaper.
This handy depriming tool is very versatile. With a universal, cylinder-style cartridge-holder, the tool can deprime a wide variety of cartridge types from .20 caliber up to .338 caliber. Three different plastic collets are provided to handle for different diameter cases. Spent primers are captured in a removable spent primer catch tube. Simply twist off the clear catch tube to dump the spent primers. With die-cast metal construction, this tool should last through many thousands of depriming cycles. MSRP is $54.99. Right now it is $52.00 on Amazon with 81% 5-star ratings.
User Modifications — Grip Padding and High-Volume Capture
Many users recommended putting some kind of padding on the grip and front lever to reduce pressure on the fingers. This can be done with a wrap or a rubber covering. In addition, users have adapted the unit with an attached hose and large primer capture jug. If you depriming hundreds of cases at a time, this hose conversion may make sense.
Review from actual owner: “I have owned one of these for about eight years and deprimed over 10,000 cases with this tool. I have never had to replace a single part on it. You will have to adjust the return spring every so often, but that is a very easy task. If you are depriming a LOT of brass, the handle can tear up your hand a bit. Solution: Wear a Mechanics Glove. Easy Peasy! You will NOT regret this purchase.”
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.
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, $439.99 at Cabela’s, 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 $197.99 at Midsouth Shooters.
Shiny brass — it may not shoot more accurately, but it does make you feel better about your hand-loaded ammo. While it’s not necessary to get brass “bright and shiny” after every firing, it is a good idea to clean powder residue, grime, and grit off your brass before you run cases into sizing dies. There are many ways to clean cartridge cases. A quick wipe with solvent on a patch may suffice for recently-shot cases. Older brass with baked-on carbon may require lengthy tumbling. Ultrasonic cleaning is another popular option that gets your brass clean inside and out.
Sinclair International has a series of helpful videos on brass cleaning. These short “how-to” videos, hosted by Bill Gravatt, Sinclair’s past President and current Creedmoor Sports President, cover the various processes you can use — tumbling, ultrasonic cleaning, chemical cleaning, and cleaning by hand.
Video ONE — Cleaning Brass in Vibratory or Rotary Tumbler
TIP: Brass that has recently been shot will clean more easily than brass that has been sitting many days or weeks. If your tumbling media is fresh the job should be done in an hour or less. It’s your choice whether to tumble with primers removed or with primers still in the cases. If you choose to tumble with primers out, we suggest you deprime with a depriming die, rather that put dirty brass into your sizing die. Some people like to add a teaspoon of liquid polish to the media. This does work, cutting tumble time, and making your brass more shiny. However, if you add liquid polish, do that BEFORE you add the brass and let the tumbler run for a 15 minutes to get the polish completely mixed into the media. Otherwise you can else up with gooey gunk inside your cases — a very bad thing.
Video TWO — Ultrasonic Case Cleaning
TIP: There are many different types of solutions you can use. Soapy water suffices for some folks, particularly if you add a little Lemi-Shine. The Hornady One-Shot Sonic Clean and Lyman Turbo Sonic solutions both work well, and can be used multiple times, provided you strain the solution to remove dirt and grit after cleaning sessions. Many ultrasonic cleaning machines have timers. Experiment with dwell time to see how long you need to immerse your brass. A very small amount of Ballistol in the solution will help lubricate your necks on the inside. This can make bullet seating go more smoothly, with more consistent neck tension.
Video THREE — Chemical Cleaners (Soaking without Ultrasound)
TIP: After using chemical cleaners, such as the Iosso solution, you need to water-rinse your brass thoroughly. A kitchen strainer helps with this (see video at 0:20). Also, don’t forget your brass in the chemical solution — follow the manufacturers recommendations and don’t exceed the recommended dwell time. Chemical cleaners work surprisingly well to remove grease and grime, and the solution can be re-used multiple times. However, if you want your cases to look bright and shiny (like new brass), you will probably have to tumble. [Editor: A very effective new chemical cleaner is the Brass Monkey product from the makers of Wipe-Out and Carb-Out. Add a teaspoon to a gallon of water then soak your brass for 20-30 minutes. It really works — the cases clean up dramatically].
Video FOUR — Manual Cleaning (By Hand)
TIP: Keep some oversize patches in your range kit. At the end of your shooting sessions, wipe off your fired brass with a patch dampened with a mild, non-corrosive solvent (once again Ballistol works well). Before the carbon sets up on your brass it is very easy to remove. For tougher jobs, you can use 0000 Steel Wool (as Bill recommends in the video). You may find that timely hand-cleaning lets you avoid tumbling altogether — or you may choose to tumble (or ultra-sound) your brass only after a half-dozen or so firings.
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.
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, $399.99 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 $189.99 at Midsouth Shooters.
Many shooters prefer to deprime their brass before resizing. That way they can tumble cases or keep primer debris off their main press. To deprime cases before sizing or cleaning you can use a Decapping Die. This pushes out the spent primer without changing the neck or body of a case. Such decapping dies work fine, but they do require the use of a press. Here is a handy alternative — a cool tool that allows you to deprime brass anywhere — no press needed.
Handheld Primer Removal Tool From Frankford Arsenal
This cleverly-designed Hand Deprimer Tool allows you to deprime cartridge cases without a press. This hand-tool from Frankford Arsenal will deprime brass and capture primers conveniently. You can deprime your cases while watching TV or relaxing in your favorite chair.
This device lets you remove spent primers anywhere — no press needed and all the mess (cups/anvils/residue) stays in the capture chamber. This tool comes works with nearly all common case types up to .338 Lapua Magnum. With good leverage, this tool does the job quickly and efficiently. Forum members have praised this handy tool, but recommend wearing a thick glove if doing more than 100 cases in a session.
This handy depriming tool is very versatile. With a universal, cylinder-style cartridge-holder, the tool can deprime a wide variety of cartridge types from .20 caliber up to .338 caliber. Three different plastic collets are provided to handle for different diameter cases. Spent primers are captured in a removable spent primer catch tube. Simply twist off the clear catch tube to dump the spent primers. With die-cast metal construction, this tool should last through many thousands of depriming cycles. MSRP is $54.99. Right now it is $47.98 on Amazon with 82% 5-star ratings.
User Modifications — Grip Padding and High-Volume Capture
Many users recommended putting some kind of padding on the grip and front lever to reduce pressure on the fingers. This can be done with a wrap or a rubber covering. In addition, users have adapted the unit with an attached hose and large primer capture jug. If you depriming hundreds of cases at a time, this hose conversion may make sense.
Review from actual owner: “I have owned one of these for about eight years and deprimed over 10,000 cases with this tool. I have never had to replace a single part on it. You will have to adjust the return spring every so often, but that is a very easy task. If you are depriming a LOT of brass, the handle can tear up your hand a bit. Solution: Wear a Mechanics Glove. Easy Peasy! You will NOT regret this purchase.”
How to Adapt Tool for Small Flash Hole Brass
The Frankford Arsenal Deprimer Tool was designed for LARGE flash-hole brass. To deprime brass with small (1.5mm/0.59″) small flash-holes, as found on Lapua .220 Russian and 6mmBR cases, you will need to reduce the pin diameter. Frankford Arsenal currently recommends purchasing a replacement pin and “sanding it down” to the smaller diameter. NOTE: This is NOT difficult — simply spin the stock pin in some sandpaper.
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.
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.
Shiny brass — it may not shoot more accurately, but it does make you feel better about your hand-loaded ammo. While it’s not necessary to get brass “bright and shiny” after every firing, it is a good idea to clean powder residue, grime, and grit off your brass before you run cases into sizing dies. There are many ways to clean cartridge cases. A quick wipe with solvent on a patch may suffice for recently-shot cases. Older brass with baked-on carbon may require lengthy tumbling. Ultrasonic cleaning is another popular option that gets your brass clean inside and out.
Sinclair International has a series of helpful videos on brass cleaning. These short “how-to” videos, hosted by Bill Gravatt, Sinclair’s past President and current Creedmoor Sports President, cover the various processes you can use — tumbling, ultrasonic cleaning, chemical cleaning, and cleaning by hand.
Video ONE — Cleaning Brass in Vibratory or Rotary Tumbler
TIP: Brass that has recently been shot will clean more easily than brass that has been sitting many days or weeks. If your tumbling media is fresh the job should be done in an hour or less. It’s your choice whether to tumble with primers removed or with primers still in the cases. If you choose to tumble with primers out, we suggest you deprime with a depriming die, rather that put dirty brass into your sizing die. Some people like to add a teaspoon of liquid polish to the media. This does work, cutting tumble time, and making your brass more shiny. However, if you add liquid polish, do that BEFORE you add the brass and let the tumbler run for a 15 minutes to get the polish completely mixed into the media. Otherwise you can else up with gooey gunk inside your cases — a very bad thing.
Video TWO — Ultrasonic Case Cleaning
TIP: There are many different types of solutions you can use. Soapy water suffices for some folks, particularly if you add a little Lemi-Shine. The Hornady One-Shot Sonic Clean and Lyman Turbo Sonic solutions both work well, and can be used multiple times, provided you strain the solution to remove dirt and grit after cleaning sessions. Many ultrasonic cleaning machines have timers. Experiment with dwell time to see how long you need to immerse your brass. A very small amount of Ballistol in the solution will help lubricate your necks on the inside. This can make bullet seating go more smoothly, with more consistent neck tension.
Video THREE — Chemical Cleaners (Soaking without Ultrasound)
TIP: After using chemical cleaners, such as the Iosso solution, you need to water-rinse your brass thoroughly. A kitchen strainer helps with this (see video at 0:20). Also, don’t forget your brass in the chemical solution — follow the manufacturers recommendations and don’t exceed the recommended dwell time. Chemical cleaners work surprisingly well to remove grease and grime, and the solution can be re-used multiple times. However, if you want your cases to look bright and shiny (like new brass), you will probably have to tumble. [Editor: A very effective new chemical cleaner is the Brass Monkey product from the makers of Wipe-Out and Carb-Out. Add a teaspoon to a gallon of water then soak your brass for 20-30 minutes. It really works — the cases clean up dramatically].
Video FOUR — Manual Cleaning (By Hand)
TIP: Keep some oversize patches in your range kit. At the end of your shooting sessions, wipe off your fired brass with a patch dampened with a mild, non-corrosive solvent (once again Ballistol works well). Before the carbon sets up on your brass it is very easy to remove. For tougher jobs, you can use 0000 Steel Wool (as Bill recommends in the video). You may find that timely hand-cleaning lets you avoid tumbling altogether — or you may choose to tumble (or ultra-sound) your brass only after a half-dozen or so firings.
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.
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.
As a cartridge case is reloaded multiple times, burnt powder residue and carbon builds up on the inside of the case. Unless the case interior is cleaned in some fashion, eventually you’ll see a slight reduction in case capacity. One of our Forum members from Australia wonders about the effects of reduced case capacity: “If the capacity of the case decreases as the crud builds up, then it effectively reduces the size of the cartridge (inside). Wouldn’t that change the pressure produced from that of an equivalent clean case?”
Interesting Test of Case Capacity Changes
Forum member Fred Bohl has actual test results that can help answer the above question. Fred proved that, over a 20-reload cycle, the case capacity of uncleaned cases did decline a small amount. However, surprisingly, this did not seem to affect the actual chronographed velocity of the load. Extreme Spread (ES) did increase, but Fred believes the higher ES was due to changes in case-neck tension, rather than due to the slight reduction in case capacity. Fred reports:
“Back when beginning to use ultrasonic case cleaning, part of the motivation was to get the inside clean based on the assumption that allowing burnt residue to build up inside cases would affect capacity, and, ultimately, performance. An experiment was done to test this hypothesis. The load used, 30.5 grains of RL15 behind 107gr SMKs in a 6mmBR, was selected for best group and lowest ES in prior load development. It turned out to be 92% of initial case capacity and neither “full” or compressed. (I would suspect that different powders, load weight, and total case capacity might produce very different results.)
We took 30 cases of identical initial capacity and tracked three lots of 10 each:
LOT 1: No Internal cleaning LOT 2: Cleaned with media in tumbler LOT 3: Cleaned with Ultrasound machine
Each case (in each lot) was shot and reloaded 20 times. The simplified results after 20 reloads of each lot were as follows:
Lot 1 (not cleaned) – 0.3 to 0.4 gr. loss of capacity, 5 to 8 fps greater ES.
Lot 2 (tumble cleaned) – 0.1 to 0.3 gr. loss of capacity, 4 to 6 fps greater ES.
Lot 3 (ultrasonic cleaned) – no loss of capacity, no detectable change in ES.
FINDINGS There was no detectable correlation of velocity change to the lots. An oddity was that on very hot days Lot 1 velocities were, occasionally, slightly higher. From results of another ongoing test, I believe the above differences in ES are probably due more to variance in bullet grip tension than case capacity. The ultrasound cleaned cases (LOT 3) did maintain the lowest ES, but we are not 100% sure of the reasons why. More consistent bullet seating might be the reason.”
Editor’s NOTE: Fred’s results do suggest that carbon build-up inside the uncleaned cases might cause a slight increase in pressure that shows up on hot days. Fred has posted that: “A local shooter reported doing the 20 reload, no-clean test on a .308 that gave a loss of capacity of 2.0 grains, doubled ES and significant velocity changes. However, I don’t have any details on his load weight or powder.” Obviously a lot of carbon can build up with 20 reloads. Many shooters retire their brass before then.
Ultrasonic Cleaning and Neck Lube
Some time ago, Jason Baney did a lengthy test on ultrasonic cleaning. Jason found that with his ultrasonically-cleaned cases, the inside of the necks got so “squeaky clean” that he needed to use dry lube in the necks. Jason uses the $21.50 dry lube kit from Neconos.com. This applies ultra-fine Moly powder to the neck interior using small carbon steel balls.
Shiny brass — it may not shoot more accurately, but it does make you feel better about your hand-loaded ammo. While it’s not necessary to get brass “bright and shiny” after every firing, it is a good idea to clean powder residue, grime, and grit off your brass before you run cases into sizing dies. There are many ways to clean cartridge cases. A quick wipe with solvent on a patch may suffice for recently-shot cases. Older brass with baked-on carbon may require lengthy tumbling. Ultrasonic cleaning is another popular option that gets your brass clean inside and out.
