Black spots on brass after tumbling?

Duster340 · May 19, 2019

Hey Folks,

Preparing you start reloading for my new 30-06 7400. Tumbling a bunch of old mixed brass I received last year with a bunch of other stuff. (Glad I held onto it!). Using my standard walnut shell media with a bit of Flitz, which historically gets even the grubiest brass sparkling clean.

I noticed some of the tumbled brass has black marks/spots on the cases and on necks of the casings. Remington seems to be the worst, but some Winchester and few Federal cases have the spots.

The spots are smooth and can't be felt with my finger nail. They appear to be cosmetic and I'm not adverse to loading them up. But thought I'd ask fellow THR reloaders if they have experienced this and should I be concerned using them.

Here's a couple examples of the worst cases.

Thanks much!

Series70 · May 19, 2019

I only do pistol brass. Have seen similar black spots like last photo occasionally. No problems after shooting the cases. I don't remember seeing extensive blackening such as what is around your case necks.

Bandit67 · May 19, 2019

They may be fine but since .30-06 brass is cheap and plentiful I would scrap it.
Personally I'm more interested in what's aging in those little oak barrels. Lol.

Duster340 · May 19, 2019

Bandit67 said:
Personally I'm more interested in what's aging in those little oak barrels. Lol.

LOL.. Good eye bandit

Nothing fancy in these, one's Jim Beam, a vanilla bean pod and 2 roasted coffee beans. The other is Dewars White Label with some Crown I had laying around. Have a few more charred barrels with various concoctions in the wings as well. 3-6 months really changes the flavor profiles and results in super smooth sipping sauce. Like handloading, started with one little barrel....and grew into an obsession! Lol.

Be well

Random 8 · May 19, 2019

These are normal with older brass. They are latent corrosion, but not set in enough to compromise the strength of the brass. If you find them that appear green/blue or pitted on the surface, discard. I do cull them from ammunition destined for hunting, as they will be a hotspot for more corrosion to set in during damp weather.

The black around the case mouths is either above latent corrosion or powder residue driven into the surface of the brass. I find this commonly with "ball" powders and RL-15 in high pressure cartridges.

Try a cardamom "berry" and/or clove in one of those barrels.

Duster340 · May 19, 2019

Thanks Random8. That makes sense, I was told the brass may have been sitting in a cardboard box for 15+ years I'll cull out the worst of the worst, and use the rest of the discolored ones for plinking loads. Got over 200 nice clean cases to use for hunting loads so far with another batch in the tumbler.

And thanks for the tip on the cardamom & clove. I just so happen to have an empty barrel waiting in the queue

Catpop · May 19, 2019

Looks like spot electrolysis to me!

Slamfire · May 20, 2019

Duster340 said:
Thanks Random8. That makes sense, I was told the brass may have been sitting in a cardboard box for 15+ years I'll cull out the worst of the worst, and use the rest of the discolored ones for plinking loads. Got over 200 nice clean cases to use for hunting loads so far with another batch in the tumbler.

And thanks for the tip on the cardamom & clove. I just so happen to have an empty barrel waiting in the queue

It just looks to be surface corrosion, and since it is on the case neck, not the case head, I would not worry about it.

The safety critical section of a case is the case head.

You have a crack, or rupture in the unsupported area of the case head, and the gas release can cause catastrophic failure of the mechanism.

But, a little corrosion on the case neck, not safety critical as long as any cracks stay in the case neck

gojones · May 20, 2019

I started out reloading 30-06 back in the 70's. All were from fired military brass. Our the years I have encountered many that had some very small amount of "black spots". They never compromised the brass. I remember cutting one open and found that it was only surface discoloration and did not eat into the brass. Got about 6-8 firings from them. I think you are fine with these.

Rule3 · May 20, 2019

Take some extra fine steel wool (or synthetic) with some Flitz and rub, See if it comes off.

I am interested in those little barrel also, please PM me on where you get them and what procedure.

Black spots on brass after tumbling?

Duster340

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Random 8

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