Back in what feels like another life at this point, I can visualize the guns/ammo that were hidden by immersing them in honey pits (outdoor toilets), buried in swamp mud and even in used cooking oil.
With a bit of TLC, they were never pretty but they all went bang, without any issues, other than the very odd failure to feed.
Milspec ammo is meant to be stored under outrageous conditions and with very little fuss, be washed off, stuffed into magazines and loaded/fired from the platforms they were designed for.
One of the few times I can remember this being an issue, was before my own time in the field, and it involved the first American ARs that went into service.
Why it wasn't picked up in the extensive testing before being accepted ???????????
There are many here much more familiar and knowledgeable about these ammunition issues than I am, but basically the rifles suffered from all sorts of issues, such as failures to feed and go into battery from dirty ammo, wrong propellants etc. They had enough trouble that they incorporated a ''forward assist'' mechanism to help push bullets into the chamber with pressure applied by the butt of the soldier's hand, which usually got things working as intended.
Nothing worse than being in the middle of a stressful situation and getting a failure to feed, seat or go bang. Right when you least need that to happen.
Those old Soviet designed firearms and their ammo were and still are exceptionally reliable. They're not as tight or slick as the AR and other platforms but any one can operate them after a few minutes of training and the components are very strong, sloppy and acceptably accurate for the purpose they were designed for.