In my younger days when my knees were still good, I carried a backpack. I had a spare 100 rd plastic box of CCI Mini Mag in a side pocket of the pack along with a spare plastic bottle of liquid “backpackers” soap that was supposed to be environmentally safe. I liked it because it lathered well in cold water. These two items were “spares” and I never had occasion to use either one so that particular pocket was never opened.
A few years went by and I was cleaning out my pack and decided to rotate the ammo and use it up. To my surprise, fully half of the rounds in the box were duds. The rounds that fired seemed fine but the duds would not fire even after rotating the cases in the chamber and trying them a second time.
I’m thinking the liquid soap put off some form of vapor that attacked the priming compound in the ammo after years in such a confined space.
Since then, I’ve shot many thousands of rounds of CCI ammo and have not had a single dud round.