Corossion on black powder fired brass

[greyhawk]

I shot last sunday, cleaned the rifle when I got home, left the empty brass in with the loaded stuff in one of those green plastic carry boxes till I remembered it wednesday, deprimed and dropped it in a small bottle of water and gave it a shake, mrs asked me to do something for her before she left for work, bottle got left on top of my car in the garage, remembered this morning (saturday), now where the heck did I leave that bottle, found him this afternoon, yuk! shells were black and orrible looking - couple rinses, 19 minutes in the ultrasonic cleaner in some citric acid solution. rinsed a couple times, they gone pink, bit of a rub with some steel wool they good as new -- thing I like most about the ultrasonic they come out spotless clean inside and the primer pockets too - usually a bit dull outside but dont take much to shine em. This was just twenty 45/75 shells - so the steel wool by hand was easiest to polish em (dont usually bother with shiny but these were pink)           

[David Battersby]

I shoot lever action silhouette, and in the course of a year I shoot A LOT of 44WCF black powder.   Any cases that have been forgotten after shooting will start to get a little white and fuzzy on the inside. I do mean start to get a little white and fuzzy. I have never had green on the inside or outside of any fired brass using black powder.

[Robert Swartz]

.....in cleaning BP cartridge brass. I usually take a jug of water to the range, sometimes I don't. Sometimes I don't get to the brass for a couple days or so. When I do, I have a dedicated deprimer die, after that I run the brass through three full cycles in my  (Harbor Freight) ultrasonic cleaner. Use a pinch of Lemishine and Dawn dishwasher liquid. Then wash in cold water. Let dry a bit then off to the tumbler. I use coarse corn cob (50lb bag from the farm store) with a pinch of NuFinish car wax. Looking at the shells of the OP.....I've had some ugly brass but shooting real black, never had anything look like that. That residue just screams Pyrodex to me.

[greyhawk]

I shoot lever action silhouette, and in the course of a year I shoot A LOT of 44WCF black powder.   Any cases that have been forgotten after shooting will start to get a little white and fuzzy on the inside. I do mean start to get a little white and fuzzy. I have never had green on the inside or outside of any fired brass using black powder.

Leave em long enough they will go green

[Blackpowder Burn]

Green corrosion or "slightly fuzzy" depends on the climate they are in.  In the humid area I live they quickly get green copper corrosion products.  However, it's all minor surface corrosion, just looks bad.  Toss them in a wet tumbler and look good as new.  Stop overthinking it............