Has anyone had issues with the copper wash coming off and staying inside the chamber? My friend had that happen a lot with the Norinco 308 that was copper washed but I've never noticed it with the 7.62x54R in my Mosin or SVT-40.
FWIW:
Steel cases will, of course, rust pretty quick if not coated. Modern steel cased stuff is laquered or coated in a polymer of some sort. That's where you get the green coloured 7.62x39 all over the place. The copper wash method is older and serves the same purpose; prevent the steel underneath from rusting. It's not a true copper plating and many people online say it's done after the ammo is assembled so the bullets and all get a copper wash. That seems to be possible with some ammo but I've got others where there is definitely a colour difference on the primers. I'm not sure exactly how the copper is applied but I would guess some sort of bath with copper dissolved into it. An acid perhaps? Maybe it is a form of mild electro plating? I'm sure someone knows.