I've stored magazines and stripper clips in the no rust poly bags for the five year shelf life and never had any rust or corrosion problems.
I used to buy them from a guy in Irwin, PA. He used to sell them at the PGCS gun show.
His website was
www.norustbags.com but that url is dead.
I found this outfit
https://www.rustfreebags.com/Page_1.php and I think it's the same guy because the bags are yellow and if you pay by check the check is to be made out to "no rust bags".
His products are cheaper than Bianchi's "blue bags".