I was given 100 rounds of surplus Yugo 8mm rifle ammo that had lots of green residue on the brass. I used Simple Green, full strength, which removed the green stuff. Then I wiped each round with a wet towel and dryed with tissue. The rounds fired fine in my Mauser.
As long as you wipe them dry after cleaning it might work.
Don't know about using Brasso, it might be a little too strong.
And if the ammo is pitted from corrosion or the residue is hardened it might be best to discard.
Just my opinion.
Thanks for thr reply Chris. I am using Mothers Mag Polish. It does a good job but is very slow. I am going to phone Federal and ask them if a vibraor "tumbler" will damage the powder composition. I'll let you know.
To those that might be interested. I spoke to the Tech Guy at Federal. He said do not tumble or vibrate live ammo. The "knocking about" of the powder in the round will remove the chemical coating on the powder that controls burn rate and will increase the pressure when fired. He further said do not use any type of metal polish as that will harden the brass and make it unusable for reloading. His recommendation was to use steel wool to clean the tarnish or corrosion or to simply shoot it as is. He gave me some horror stories to prove his point..
Back a few years (OKOK....a LOT of years) I came into a large lot of badly corroded WWII ammo.
Tumbling didn't seem to do much (and I had the same concerns the Federal guy voiced) so I tossed a double-handfull of lathe chips into the tumbler rather than keep at it with the corncobs. Cleaned them right up in a matter of minutes, with what I judged a lot less vibration than they'd get in a box on the floor of the pickup riding home from the store.
As an aside, most of the ammo shot fine if you sorted it by shaking it. A dull sound meant the powder had got wet. I used it for hipower competition when I was a youngster.