Originally Posted by
togor
If one has a batch of suspect ammo in-hand, testing is a relatively straightforward process. Pull a bullet and dump the powder, and fire the primer such that the residue is deposited on a brightened piece of steel like a lawn mower blade or some bar stock hit with a wire brush or angle grinder. Can be useful to similarly fire some known non-corrosive and corrosive primers as controls on nearby spots. After a few days, you'll know. It doesn't hurt to bring the steel into areas of higher humidity, such as the bathroom while someone showers.