I'd like to know if commercial loaded ammo is treated for anything with brand new clean brass. I'd bet pretty highly not.,
I asked one of the big ammo producers (Federal, IIRC) if they take any measures to prevent cold weld. The response I received read something like "huh...what's that?"
I've though of things I might do to prevent it when I've tumbled in stainless pins (which I do every third or fourth loading, I guess). One is to dip the necks in Turtle Was Zip Wax and stand them on their mouths for a few days to dry. I have no idea whether it would work but I may give it a try.
Another is to treat jacketed bullets the same way.
I may get around to it someday.