Brass Corrosion

[TheLucasRanch]

Hello all - wonder if you experts can help? After tumbling a batch of 82-count Lapua 14x fired cases, I noticed three of them had this corrosion/pitting in the same middle part of the body. Please see pics attached. All the other cases are in great shape, annealed every 4x firings, etc. Can anyone suggest what might be the cause? One hypothesis was that I left copper cleaning solvent in the chamber and the first few rounds after the cleaning picked it up. Since they’re all in the same spot that seems to make sense. Has anyone else had this happen? Thank you for your feedback. I guess that could be a weak spot now, and these should be trashed?

 

[DShortt]

Never saw a solvent attack brass like that even if left on there a long time. Let alone residue left in the chamber that transferred.
But you've got 14 firings on this brass?
How old is it and how long has it been sitting around?

 

[TheLucasRanch]

Never saw a solvent attack brass like that even if left on there a long time. Let alone residue left in the chamber that transferred.
But you've got 14 firings on this brass?
How old is it and how long has it been sitting around?

Thanks. They were new, unfired cases about 4 years ago. Yes 14 firings. The others in the batch are in great shape, no signs of stress. They generally sit around for a few months between firings until I get around to cleaning and reloading them. I’ve noticed the slight discoloration on previous recent reload cycles and passed it off as a surface blemish, but this is the first time I’ve noticed the severe pitting and corrosion.

 

[Coyotefurharvester]

Usually oxidation (pitting the surface) on rifle brass is visually green, did you clean off the green for pics?
Salt/acid and moisture are normal contributors. Your fingers can transfer acid/salt(sweat) which when moisture is added will oxidize brass. Is that location on the brass where you normally touch them?

 

[searcher]

I'm inclined to agree with your hypothesis. To me, that definitely appears to be chemically induced corrosion. I'd toss the cases that exhibit such corrosion and keep the remaining that show none to very little - keeping an eye on them after each firing.

 

[whatsupdoc]

Brass tarnishing "oxidation" will turn brass black. That looks like a chemical attack that removed the
zinc.

You weren't eating fried chicken and reloading were you?

 

[Webster]

Hello all - wonder if you experts can help? After tumbling a batch of 82-count Lapua 14x fired cases, I noticed three of them had this corrosion/pitting in the same middle part of the body. Please see pics attached. All the other cases are in great shape, annealed every 4x firings, etc. Can anyone suggest what might be the cause? One hypothesis was that I left copper cleaning solvent in the chamber and the first few rounds after the cleaning picked it up. Since they’re all in the same spot that seems to make sense. Has anyone else had this happen? Thank you for your feedback. I guess that could be a weak spot now, and these should be trashed?

View attachment 1672940View attachment 1672939View attachment 1672941

Strange that the corrosion would happen at the same location on 3 cases. Pitting corrosion like you have is unusual you would expect stress corrosion. I would expect corrosion would be more likely on the necks. I guess my only comment would be that many copper removal bore cleaners contain ammonia. Ammonia is a big corrosion promoter. Sweets cleaner has a lot of ammonia in it. I think Butches Bore Shine also has some ammonia. Are you doing something that would get ammonia on the cases? Even very brief exposer can be bad. Chlorine is also a big corrosion promoter.

After shooting at the range I clean with Butches bore cleaner , run several dry patches thru, then fire 1 shot to condition the bore in case I go GH hunting. I assume the shot dries the bore.

 

[TheLucasRanch]

Strange that the corrosion would happen at the same location on 3 cases. Pitting corrosion like you have is unusual you would expect stress corrosion. I would expect corrosion would be more likely on the necks. I guess my only comment would be that many copper removal bore cleaners contain ammonia. Ammonia is a big corrosion promoter. Sweets cleaner has a lot of ammonia in it. I think Butches Bore Shine also has some ammonia. Are you doing something that would get ammonia on the cases? Even very brief exposer can be bad. Chlorine is also a big corrosion promoter.

After shooting at the range I clean with Butches bore cleaner , run several dry patches thru, then fire 1 shot to condition the bore in case I go GH hunting. I assume the shot dries the bore.

I did use Sweets to clean the chamber. I think you may be onto something. Thanks.

 

[ELR LVR]

Hello all - wonder if you experts can help? After tumbling a batch of 82-count Lapua 14x fired cases, I noticed three of them had this corrosion/pitting in the same middle part of the body. Please see pics attached. All the other cases are in great shape, annealed every 4x firings, etc. Can anyone suggest what might be the cause? One hypothesis was that I left copper cleaning solvent in the chamber and the first few rounds after the cleaning picked it up. Since they’re all in the same spot that seems to make sense. Has anyone else had this happen? Thank you for your feedback. I guess that could be a weak spot now, and these should be trashed?

View attachment 1672940View attachment 1672939View attachment 1672941

Do you ever get mice?
I had a mice infestation come in through the water heater closet once
Drove me crazy trying to find out how they were getting in
I'd be asleep and a mouse would suddenly be running by my bed haha
ticked me off, irritating, turn on the light and he was gone so could never find him
kept catching them in traps and found they were breeding so every time I got one another one would pop up.
They chewed a hole right through the wall to get in, small hole near a 2x4, could barely see it
Steel wool stuffed in there cured it once I found it. They don't like chewing on steel wool.
---------------------------------------
So their pee is very corrosive, must be a high concentration of ammonia
and some got on my brass and did what you're describing
Mice is the only thing I can think of

 

[Straightshooter1]

I did use Sweets to clean the chamber. I think you may be onto something. Thanks.

. . . and it might be a combination of that plus case stretching after 14 firings?

I've got 16 firings on my .308 cases and they're still looking pretty good.

 

[K22]

Couple of thoughts from an old brain,

1. The only time I ever had any tarnish on my cases is when I handled them in very humid conditions in the field while ghog hunting. This was clearly the result of the salty sweat on my fingers that transferred to the cases and my failure to wipe them off. However, this never affected performance, and it didn't look anything like your pictures.

2. I do not use aggressive copper solvents so I cannot comment on their effect on cases. However, I always make sure the chamber is free of any oil, solvents, greases, etc. If you use a bore guide with a rubber O-ring and tilt the rifle at an angle, there shouldn't be any solvent migrating to the chamber. Before pulling the bore guide out, run a dry patch with a pistol rod down the bore guide this will remove any solvent remaining in the bore guide and prevent dumping in the chamber or action. Dewey 9" brass rods are perfect for this function since they are inexpensive and do not rotate. Use a looped jag to retain the patch.

3. Your picture looks like stress corrosion cracking I've seen in industry. I would thus suspect, something reactive came in contact with the cases but this is only supposition. Ammonia is very corrosive, and Sweets is ammonia on steroids. It's why I would never ever use it in any of my rifles. Beside removing all the copper which has served to fill the imperfections of the rifling re-exposing them thus creating the need to re-condition the rifle to regain desire POI, this stuff can damage the bore if not used cautiously. Furthermore, it my experience it is totally unnecessary despite what the "experts" claim, at least in my experience for my use.

 

[ebb]

I once had someone look at my brass and asked what the ring around the brass was, was the chamber grooved. Several others looked and insisted it was a bad chamber. They had been in a 100 round MTM box and rattled in the box on the truck ride to the range and the holes in the plastic box had made the ring, Could the band of corrosion be at the same height as the upper divider of the box and may be while shooting something dripped on them? Could even be sweat dripping off of your hand if you've ever shot on a very hot day. i hope you find this was a minor problem and not a big one.