Was this in a Vibrator type "tumbler", a rock polisher type tumbler, or one of your commercial "Cement Mixer" type tumblers?I have on two occasions had a cartridge have it's primer hit hard enough to cause it to go off by another cartridge.
Thanks for all the replys.The warning "Do not tumble live ammo" is getting to be worn out. Even the article presented above is equivocal on the subject. Pointed out how one "commercial entity" merely warned about "prolonged tumbling". Several other members of the same "accurate shooter" forum have tumbled rounds hours, in some cases days, pulled them down and examined the powder under a microscope, and found no degradation.
If all the arguments were true then the Military wouldn't transport live ammo in helicopters, especially the old Huey. All that vibration for up to hours of transit would be "damaging the ammo". Just think how much vibration and jousting about your powders have been subjected to just traveling across the country in the back of a freight truck.
Yes, manufacturers do "finish" ammo in a vibrator/tumbler without harm. I've been doing it for well over 30 years and performance wise still am able to shoot "one hole groups" with it.
All this said, the use of a tumbler/vibrator would not be recommended in your case. It's a good chance that the tarnish or verdigris on the cases is more than just on the surface. If the brass is severely discolored no amount of tumbling will polish it out unless you remove a significant amount of material.
I'd consider just wiping the cases with a rag and some Nu-Finish Car polish. There is just enough solvent and polishing compound in the Nu-Finish product to remove any surface "crud" and leave a good shine, unless the brass is severely corroded.
If smokeless powder was that sensitive then it would be transported like dynamite. You wouldn't be able to buy it and have it shipped to your house by UPS.Kinda like shaking dynamite - even though that probably won't set it off.
It just feels wrong from the get go...if you know what I mean.
Not just tumbled a lot but he brass usually has the primer pockets drilled out by a "counter bore". They sure know how to ruin good brass. Maybe they don't want anyone reloading it.In my experience, I can say the Blue Box Black Hills 223 Rem rounds definitely look like they were tumbled, a lot!