Recently I've noticed some bluish colored corrosion on a few of my older reloads. Always in the same place, the mouth of the case, and the base of the bullet. Usually not all the way around, mostly about 25% of the circumference.
Only on brass cases, and only on copper jacketed bullets. Doesn't seem to be any pattern as to whether or not the round has been in one of my guns, or only in a storage box, happens in both, so I've kinda ruled out gun oil.
Since both copper and brass are basically the same combination of metals, it doesn't seem likely that this is electrolysis, so I'm lost.
Any of you gents experience this problem, and if so, what was your finding?
Thanks and regards to all.
Bob

I don't recall seeing this on handloads, only old factory ammo. Unless it was severe, I'd shoot it.

A couple thoughts; I have had some very light "blue/green" fuzz/decolorization appear at the case mouth on older cast bullet loads. I believe it was the bullet lube reacting with the case. Also had some fuzz appear around a gas check on some older cast bullets (several years old). Another thought it could be galvanic corrosion. Contact of two dissimilar metals can lead to an electrochemical process that produced corrosion (cartridge brass and bullet jacket material are not all the same and I've read of primers corroding in the pockets). It there is any corrosion in other areas, the outside of the case it's from some contamination. If there are no obvious pits on the surface then they are probably OK, I'd pull one of the bullets and see how bad it is. If the corrosion or discoloring is light, or the bullet isn't tight/stuck, I might just shoot them...

Pictures would help!

How long and where stored?

I had some .22's left in a holster rig that were really a funky bluish-greenish and kind of greasy! Not a clue how to explain it other than chemical reaction between the salts in the leather and the chemicals in the bullets.

Smiles,

Verdigris
Verdigris - Wikipedia

Probably you had some salty sweat on your fingers when handling them.

It shouldn't be an issue if that's what it is.

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Just Say No - To Social Media

Definition:

verdigris: a bright bluish-green encrustation or patina formed on copper or brass by atmospheric oxidation, consisting of basic copper carbonate.

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Pisgah

Clean with steel wool and oil and shoot them.

So true. Just wipe off and shoot.

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S&W Accumulator

Thank you gentlemen, you pretty much confirmed what I had thought. I too have experienced this same corrosion on rounds stored in a cartridge belt, and attributed it to leather dressing oils. These particular rounds have either been in a plastic shell box, or in one of my Smith .38's, always inside my house, cool and dry.
This stuff doesn't just "wipe off", I used a mini wire brush to remove it. And .... me being the original Ancient Mariner, I'm intimately familiar with verdigris. This stuff is more tenacious than that. I do plan to shoot these rounds, after a closer inspection.
Appreciate all the replies, thank you.
Bob