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Old May 19, 2019, 07:51 PM   #1
Crapshoooter2
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Any ideas about what caused the spot on shell

Crapshoooter2

Just a newbie to loading so when I come across something new to me I go to my source: The Firing Line.

I have attached a pix of a shell which has a spot. The spot has no significant depth to it, is not pitted. It is if someone had rubbed off the brass.

Some background on the shell. Since I am new to reloading, I am very careful about inspecting the shells after cleaning. I check with a go-no go and with a RBCS Micro for my records, then inspect again, so the chance of missing this spot before the last firing is almost an impossibility.

I had loaded 10 rounds, all using the same Hornady shells from the same batch, using 24.8 gr of Benchmark power, Sierra 50 gr bullet, OAL 2.245. Each shell had been fired two times. fired in a bolt action, 24 inch barrel.

After the third firing, I was looking at the shells before putting into the tumbler when I came across the spot. Only one shell had the spot and no other shell showed any other unusual marks.

I used a dental tool to see if I could feel any thing happening on the inside of the shell in the spot area and I could not. But to made sure I cut open the shell and the area inside of the shell in the spot area looked exactly like the rest of the inside of the shell.

My question is: What do you think happened?
IMG_2584 (3).JPG
Thank You

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Old May 19, 2019, 08:47 PM   #2
Pathfinder45
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I think it's chemically induced corrosion from a contaminant. Could be something as simple as sweat from your hands or a multitude of other possibilities. Chlorides are bad for copper and its alloys: https://en.wikipedia.org/wiki/Bronze_disease
I have some ammo I loaded 20 years ago that is starting to show some tarnished spots on the outside, but upon dismantling the worst round, I found all was clean and shiny on the inside. Some ammo can go horribly bad on the inside in an alarmingly short time, due to destabilized powder.
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Old May 19, 2019, 08:59 PM   #3
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Yep. The brass below was in a basement flood, but after I cleaned it up in the ultrasonic with citric acid, probing the worst places revealed less than 0.002" penetration and it still functioned fine.

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Old May 20, 2019, 07:04 AM   #4
Crapshoooter2
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Was concerned that it was some sign of stress or weakness developing in the shell.

Thanks Again
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Old May 20, 2019, 07:34 AM   #5
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I see this same stuff from Range Pickup brass, I believe it's salt or some other form of Ice Melt.
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Old May 20, 2019, 11:23 AM   #6
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I have had it as well, random, no salt on the range, maybe tracked in by feet though.

Good question though and I would throw it when I found it, its messes with my public image of perfect shiny brass!

Well that and I did not like what I saw and its very few like it
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Old May 20, 2019, 03:00 PM   #7
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It is possible that the shell has a weak spot and the cleaning solution highlighted it. Only real way to check that possibility is to cut open the shell to test the material thickness AND test the metallurgy of the spot in question. Alloy may be uneven there and could be more reactive to the cleaning solution and / or humidity.

At the end of the day - brass is cheap. If you don't trust it - scrap it.
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Old May 20, 2019, 05:00 PM   #8
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At the end of the day - brass is cheap. If you don't trust it - scrap it.
Amen to that, particularly in brass intended to go into an autoloader.

Unclenick, I'm not trying to bust on you, but I wouldn't touch that brass with a 10-foot pole. I've thrown out brass with far less corrosion spotting than that. No, I'm not a metal expert... which is why I'm so choosy... I DON'T know whats happened to that brass, what has spotted it, or if it's caused any weakness in the brass... and I don't really want to find out, if you know what I mean.
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Old May 21, 2019, 07:00 AM   #9
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I'm not a metal expert... which is why I'm so choosy... I DON'T know whats happened to that brass, what has spotted it, or if it's caused any weakness in the brass.
Pretty much my philosophy...and, to go a bit further...I don't pick up public range brass at all. YMMv, Rod
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Old May 21, 2019, 08:56 AM   #10
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Originally Posted by Charlie 98
Unclenick, I'm not trying to bust on you, but I wouldn't touch that brass with a 10-foot pole. I've thrown out brass with far less corrosion spotting than that. No, I'm not a metal expert... which is why I'm so choosy... I DON'T know whats happened to that brass, what has spotted it, or if it's caused any weakness in the brass... and I don't really want to find out, if you know what I mean.
You're not busting anything. I'm a professional engineer and wanted to have a look at the damage up close. I also sectioned some of that brass to confirm my probe measurement and that dezincification (that pinkish color you see in the places in the second image where the green, white, and black oxides were removed) had not extended below the surface, either inside or out, and it was fine. It was an experiment and not something I normally run into (the brass wasn't from my basement).

I have seen through-and-through corrosion of cases caused by nitric or nitrous acid radicals produced by powder deteriorating inside. A probe went right through to the inside. Incidentally, that also made for green and black oxides, so chlorine isn't the only possible culprit when you see those. This article mentions that "chemicals in rainwater, tap water, and air, as well as those found on our fingers and in food, are also corrosive." This other article has a nice photo of the discoloration resulting from dezincification.

Here's a 45 Auto case with a dezincified surface that I pulled out of the ground at my range and wanted to look at more closely. It was actually fine to reshape and fire, too. Again, no through and through corrosion from the inside or the outside. Dry tumbling removed the pink coloring and returned the brass to polished yellow, so it was all happening at the surface.



The most important thing about brass condition is that the head thickness not be compromised or weakened. If the head lets go, that can damage your gun and you. In these cases, lack of penetration of the thinner parts of the case proved to be a good indication the head was fine. Weakening in other parts of the case can lead to separations or cracking, but these seldom do appreciable damage the way blowing a head out can.
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Old May 21, 2019, 09:12 AM   #11
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I have seen through-and-through corrosion of cases caused by nitric or nitrous acid radicals produced by powder deteriorating inside. A probe went right through to the inside. Incidentally, that also made for green and black oxides, so chlorine isn't the only possible culprit when you see those. This article mentions that "chemicals in rainwater, tap water, and air, as well as those found on our fingers and in food, are also corrosive." This other article has a nice photo of the discoloration resulting from dezincification.
See... you are talking over my head, again...

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The most important thing about brass condition is that the head thickness not be compromised or weakened. If the head lets go, that can damage your gun and you.
Unfortunately, I have had that happen... in my M1a. It wasn't fun, it wasn't pretty, but it didn't ruin me or the gun. This was with once-fired brass and shouldn't have had any problems... we are talking case head fractures (I have pictures if you want to see.) Since then, I have been a wee bit paranoid about what I can't see in brass... if it's spotted, it's out of here.
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Old May 21, 2019, 01:07 PM   #12
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Good info from Unc, I may just keep them though they have been rare.

No idea cause, I don't use anything but standard case lubes and dry polish.
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Old May 22, 2019, 09:18 AM   #13
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Cleanliness can be your enemy. Hatcher describes an experiment at Frankford Arsenal in which cases were allowed to sit on the roof of the building for a year. This was an industrial area in the 1920's before the hazards of pollutants were worked out and the atmosphere there was corrosive due to nearby chemical plants. Some of the cases were cleaned and polished, while others had the oxides left after final forming and annealing. At the end of the year, the polished cases were all corroded clear through while the oxidized ones remained intact.

I am a case polisher because I can find yellow brass in the grass more easily than oxidized brass. But if you are not firing these in a self-loader and can capture your brass as you eject it, you don't need to polish. Just decapping and cleaning in citric acid solution and rinsing and drying will give you brass whose yellow gradually deepens a bit, but which won't turn green or purple, like brass cleaned with vinegar and salt can, and won't oxidize as easily as polished brass. Indeed, I gather that a citric acid pickle is a procedure used by brass foundries to prepare a piece for long-term storage.


Charlie 98,

Sounds like a fluke. Glad you didn't suffer worse consequences. There are non-destructive methods of finding cracks and fractures in brass. I'm thinking an eddy current inspection tool might not be too hard to drum up. It would basically be a coil similar to an induction heater (but much lower power) that you set the case in and a meter that watched the high-frequency current into the coil. If there is a crack breaking up the resulting induced eddy currents, the load on the coil would drop as compared to other cases in the lot. There are commercial instruments for this, but the trick would be putting one together at a price an amateur could afford.
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Old May 22, 2019, 01:59 PM   #14
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The green colour on corroded brass is the copper coming out of the alloy. Loss of a component of an alloy is going to weaken said alloy. Probably not enough to be unsafe though.
I think Crapshoooter2's case is just the beginning of tarnish. Isn't particularly unsafe either.
A net search for "blemishes on brass cases" turns up 997,000 results. Mostly forum arguments.
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Old May 22, 2019, 02:11 PM   #15
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It often makes some folks mad, but dezincification is a real thing. I have worked on cases professionally where the brass has been so weakened that it let go at less than half of the normal cartridge pressure. If there is a pink hue, it has suffered from dezincification.

The spot on the OPs case is not dezincification, but rather localized corrosion. Probably not a big deal. Can be due to a small defect in the parent brass, or a spot of an oxidizer that had favorable conditions.
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Old May 22, 2019, 02:24 PM   #16
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A net search for "blemishes on brass cases" turns up 997,000 results. Mostly forum arguments.
I have had cases that had problems, the problem? I do not have anyone I can ask so I ask myself; is this dangerous? Is the case safety compromised? Before I go through the hand wringing thing I clean the case by spinning. While spinning I use a 3M green pad first and then finish with steel wool.

A thing about spinning; if the case is compromised the case will not support the spinner in the hand drill, Not a problem, I had rather find out the case neck has little ability to hold the bullet.

For all of you neck tensioners out there, I got nothing for neck tension, I have tension gages but none of them measure tension, they all measure in pounds.

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