The Perils of Ultrasonic Cleaning — Some Advice on Bullet Seating
Our IT guy, Jay (aka JayChris in the Forum), was having some issues with his .260 AI. A load with known accuracy had suddenly and mysteriously stopped shooting well. Jay couldn’t figure out what was going wrong. Then he remembered he had cleaned his brass using a powerful ultrasonic machine.
He inspected his brass carefully and saw that the ultrasonically-cleaned necks were so “squeaky clean” that he was actually scratching the jackets on his bullets when seating them. As well, Jay noticed that it took more force to seat the bullets and the seating force became less uniform case to case. Jay solved the problem by applying NECO Moly dry-lube inside the necks of his brass before seating the bullets.
The Perils of Ultrasonic Brass Cleaning by JayChris
I rotate my brass so that I can keep track of each firing, so I keep a “clean/ready to load” bin and a “fired” bin. I have 400 pieces of .260 AI brass. So, all of it was on its first firing (after doing a Cream of Wheat fire-forming) until I hit the 400-round mark. To my surprise, things went south at the 500-round mark. The first time I noticed it (according to my range log) was at a match last year, when I dropped several points and had some vertical stringing issues. After that match, I had 400 rounds through the barrel and all of my brass had a single firing on it. So, it was time to clean.
I have used an ultrasonic cleaner for a while now. I recently got a more powerful Ultrasonic cleaner, although I don’t know if that makes a difference. My brass comes out dry and squeaky. Emphasis on the “squeaky”.
I found that my new US machine may have been getting the necks TOO clean. After ultrasonically cleaning my brass, I had noticed that it required a little more force to seat the bullets, but I didn’t really think too much about it. But then, after going over my ordeal with a shooting buddy and going over my process in minutiae, we had an “AH HA” moment when it came to cleaning (he uses good ol’ vibratory cleaning).
So, I used some moly dry-lube to pre-lube the case necks and took some rounds out to test at 200 yards. I used my last known good load and sure enough, the vertical flyers disappeared! I shot two, 10-rounds groups with .335 and .353 MOA vertical dispersion, which is consistent with the results I was originally getting.
Other folks have suggested necks may get “too clean” after ultrasonic cleaning. It was pretty sobering to actually witness, first hand, what can happen when brass is “too clean”. I had read some discussions of issues with neck friction/bullet seating after ultrasonic cleaning, but, frankly, I dismissed the idea. Now I understand. The “too clean” effect doesn’t seem to affect my Dasher at all (perhaps because Dasher necks are very short), but on the bigger .260 AI, it definitely does.
Close-Up Photos of Case-Necks
Here are photos Jay took with a microscope. You can see the difference between tumbled brass and ultrasonically-cleaned brass. Jay says: “Here, in sequence, are the Ultrasound-squeaky-clean case neck, a case neck after treatment with NECO moly dry-lube (you can see the particles that will help coat the neck during seating), and, finally, the neck from a case cleaned with corncob media in a vibratory tumbler. You can clearly see how much smoother the inside of the tumbled neck is. Yes, it’s dirty, but it’s also very, very smooth.
Close-Up of Scratched Bullet
Here is a close-up of a bullet that was seated in an ultrasonically-cleaned (“squeaky clean”) neck, with no lubrication. You can clearly see the damage done to the jacket — in fact, in a couple spots you can see the lead core through the scratches! Jay also observed that quite a bit more seating force was required to seat the bullet in a “squeaky clean” neck.
Similar Posts:
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- Dry Lube Inside Case Necks for Smoother Bullet seating
- For Smoother Bullet Seating — The Dry Lube Option
- TECH TIP: Dry-Lube for Ultrasonically-Cleaned Case Necks
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Tags: Jay Christopherson, Moly, Neck Lube, Reloading, Ultrasonic Cleaning
It amazes me that this nonsense keeps coming up…
Sorry, they are not “too clean”. They are far from clean. There is an oxide layer left on the surface of the brass after cleaning with US. It’s blatantly visible in the first picture.
Put some 0000 steel wool around a wornout cleaning brush and run it into the neck with a drill or on the Casemate. Oxide layer will be removed and the necks will be polished and silky smooth.
Why clean to the bone to begin with? An answer looking for a problem that isnt there.
I think moly is a quick fix, but not a problem solver. Moly is hard to apply even, so some case will get more than other, also I would be worry that the oal of the bullet could change in the transport and other shocks. Steel wool works fast but you end up with steel dust, and steel being harder than brass will eat up the inside of the case neck and change the neck tension, just as moly do too. So my way is too attach the brass brush on my drill and spin until a polished case neck. Brass on Brass doesnt affect the neck and the neck tension will be more consistent with a polished brass than moly.. just my way. The only problem is that polished neck and bullet stick together after a long period of thime so check your pressure sign if you reload weeks before shooting. I took time to write this , may I ask accurate shooter to publish it, as it seems that my coment are never published. thank you in advance. Mike
Factory virgin brass can’t get any cleaner than that. They don’t have a problem either.
Try it side by side you will feel the US cleaned brass is harder to seat, it is an issue. I use both a US for 20 mins then the SS wet tumbler in a Thumbler for an hour. I dont have the issue with the thumbled brass but with just the US only cleaned brass I feel the difference.I have started using the case brush with a bit of case lube on it, about every 500 cases I put a drop of case lube on the nylon brush.
That would be because the SS tumbling removes the oxide layer. Try running a bronze brush (with or without the steel wool on it) into the neck and you will see the difference. No oxide = smooth seating.
Wow!… this is like people have washing the algae off the bottom of their boat, but leaving the barnacles and wondering why it feels rough. Then waxing the barnacles to makes things feel a bit smoother, and running with that as a solution.
I probably should have proof read that before hitting submit…
I agree with Kris that they’re not too clean. If dry moly helps, it is because it is lubing over rough brass which could be permanently smoothed by burnishing with 0000 steel wool. Likewise, this will also burnish away the sharp edge left by the chamfering tool on the inside corner of the case mouth. Having said all that, if dry moly helps, it might be easiest to simply not clean the powder soot out of the inside of the neck at all.
So, if you use the Necos molly 9or other dry lube), what happens when you add powder? some of the molly/lube mixes in the powder. Some cases pick up more molly/lube than others which in turn ends up in the powder charge.
Just a thought…
What is the cleaning solution?
If the cleaner does not contain the right brass-corrosion inhibitors or is of the wrong chemistry, the brass could be getting chemically etched. Check to see if the cleaner is labeled as that it is brass-safe. Some cleaners that are labeled “all metal safe” may not be.
If your brass comes out of the ultrasonic bath nice and shiny and does not tarnish quickly, your cleaner is probably OK. If the inside of the neck is also nice and shiny, tell us what you are using, for heaven’s sake!
Standard cartridge brass (C260) is made up of roughly 70% copper and 30% zinc. If one or both of these are etched (dissolved) out, you can get a rough surface. The surface will have a dull surface – not shiny.
Alkaline solutions tend to remove small pieces of zinc from the surface, making the surface rough. Sometimes, there are also chemical deposits on the brass.
Acid solutions also dissolve zinc, making the surface rough. I have seen this used to chemically roughen brass to get better brass/rubber adhesion.
Lots of other chemicals or mixtures of chemicals can cause problems. A very common one is triethanolamine (TEA). It is used as a rust inhibitor. It also attacks brass. TEA disolves copper, so much so that it makes a copper solution strong enough to be an algaecide. TEA also can lead to stress corrosion cracks when the brass is worked during firing and resizing.
Some cleaner solutions can oxidize the brass or deposit various chemicals. Most cleaners have numerous ingredients.
One way to find out if the problem is the cleaner bath itself is:
– Clean the brass as usual with the ultrasonic cleaner, the see if the inside surface of the neck is rough. Brand new brass may have a coating of corrosion inhibitor, so don’t test it first. Some of this coating could wash off into the cleaning bath, so run the tests on used brass first.
– Mechanically polish the neck using one of the above techniques. Do not use any kind of polishing chemicals. Rinse the neck with water.
– Run the brass back through the cleaner, leaving it in a bit longer than usual (to make the etching more visible). Rinse as usual. Repeating this step would be helpful.
– If everything looks OK, load and fire the brass with the polished necks. Clean them as usual and see if the neck looks like it got etched.
– You can try this test on new brass, but wait until you have performed the tests on used brass. If the new brass has been coated with a brass-corrosion-inhibitor, it might end up in the cleaner solution and screw up the tests. If on the other hand, enough of the corrosion inhibitor dissolves into the cleaner bath … your problem may be solved.
If the neck still looks smooth and shiny after all this, your cleaner is probably ok. You might want to repeat this test a few times, just in case. If everything is still OK, please write a comment to tell me that I am a know-nothing-Bozo (I am married, so I am used to it).
Jim