I recently processed about 600 44 magnum cases, all matched headstamps, which were stored in a very damp reloading room. They were green all over.

I popped all the primers out as a first step.

Ran them through an ultrasonic cleaner for two cycles. Then, ran them through my vibratory tumbler with walnut shell media. Then, ran them again in crushed corn cob media.

They came out looking like factory new brass! No pitting, no dangers.