Ugly brass (some sort of black residue)

[GringoLoco]

I bought some LC .223 military once-fired brass from gibrass.com. A lot of them have some sort of black spots all over them. You can actually feel it, it's like something is baked on there, not just stained. Here's a pic, the one on the left is an extreme example, most are just like the ones in the middle, and a lot are perfectly fine. My question is what is it, and what can I do about it? I hit one with a dremel with a wire brush attachment and it didn't help at all.

[Loader9]

If you're looking for quick, try Iosso. It works for me but sometimes the brass is just too bad and I trash it.

[50 shooter]

If the brass is etched/corroded to the point to where you can feel it, toss it or send it back for a refund. The last thing you'll want is a failure in your rifle, then think about that same failure when it's next to your head.

The light spots on your brass are probably okay but the ones that are covered like the one on the left I would toss or ask for a refund.

[GringoLoco]

I wouldn't ask for a refund, most of it is fine, and I was well aware before I bought it that it was bulk brass, and that some of it would be garbage. The stuff in the pic above is the worst of it, just to show what I'm talking about. Below is a pic of just a random handful of what I've tumbled so far, I just reached in and that's what I pulled out, so not bad. I'm just wondering if there's anything I can do to save the ugly stuff, and make the good stuff look pretty. You can see even on the good stuff that there's a little freckling here and there and something that looks like little skid marks. Will these dark spots come off with anything, or are they etched into the metal? What caused this?

[Gun 4 Fun]

Usually the residue that is all black like that, is powder fouling that gets between the case and chamber walls when firing. In guns with over sized or max spec chamber necks, the powder gasses can get between the case and chamber walls before the neck has completely expanded to prevent this from happening. It may not seem likely, but the hot expanding gas moves at a much higher speed than the bullet if it has anywhere else to go;i e between the neck and wall of the chamber. If you ever see a high speed video of a gun being fired,you'll actually see what I'm talking about. As the bullet exits the muzzle, the gasses pass it.
The gas gets between the case and wall of the chamber and then when the case expands tightly against the wall it practically glues the residue to the case. This condition is fairly common with military style rifles, whose actions begin extraction before the case is completely expanded. Like I said, military chambers often have oversized or max. dimention chambers to be able to function and fire reliably with all brands of ammo, under all types of circumstances.
I assume you bought your brass in bulk from someone else, who probably has access to LEO or Military range brass.

However, that first case looks like corrosion to me.
Heads-up- NEVER use Iosso or brasso to clean gun brass. They contain chemicals that will weaken brass in relatively short order. They are designed to polish brass for display, not for firearm use. There are other posts on this forum as well as others that go into detail on this. I also have severalmags. that claim the same thing.
If you need polishing agents, call Dillon Prec. Their polish works beautifully, and doesn't corrode or weaken the brass, plus a little lasts a long time in the tumbler. There are other good ones out there but I have the most experience with theirs.

[Dr. Strangelove]

I just purchased a tumbler a few weeks ago, and I've been tumbling everything that will fit into the bowl. I had some old cases from 20+ years ago that were pretty ugly, as well as some range pickups that were almost black. After tumbling, they looked pretty much the same as your last picture, with the "freckles" on them and some port-wine stain looking spots. I'm sure someone will come along who has more knowledge, but looks like to me you got some brass from an outdoor range that might have been there a while and was tumbled to pretty it up a little. As far as what to do, I dunno, I'll be watching this thread for the answer!

[AF_Reloader]

As much as I hate throwing brass away, I toss em if they have stains my tumbler won't remove, or if the case has defects I can feel with my fingernail.

It hurts, but the guy that taught me to reload didn't have either of his hands. I know that's an extreme case, but a few rounds of tossed brass aren't worth nearly as much as my .270 or my hands.

[50 shooter]

Gun 4 Fun,
Do you have a link to the info on Iosso? I have used it for years and have never had a problem with it.

Brasso on the other hand contains ammonia and will make brass brittle.

[Loader9]

IOSSO says on the label CASE CLEANER. RESTORES BRASS CASINGS TO A BRIGHT FINISH IN SECONDS. I've used it for years and it's not a problem. It contains no ammonia and is safe to use. It also states on the bottle" removes powder fouling residue, discloration, oxidation & tarnish, dirt & grime, eliminates hours of polishing in dry media". The only down side to using it is the cost.

[Gun 4 Fun]

I'll look for the article, I've got over a thousand issues of gun mags. and Gun Digests going back as far as '49. I'm not sure exactly where it is but I will look. I know it's in one from recent years. I was quoting from memory and maybe it was only Brasso, but it still seems that both were mentioned.

[Ohio Rusty]

I have .38 and .357 cases that get that on them. I found that lighter fluid on a rag cleans the cases quite nicely. That way I can still salvage some brass cases without throwing them away.
Ohio Rusty ><>

[Hawg]

I used Brasso for years before I found out car polish works just as good. If you let the ammonia evaporate before you add brass there's no problem.