there is hardware, like AKs and small caliber ammo. And as for explosives, well, TNT has unlimited shelf life unless stored in a cesspool. IIRC, about a year ago it was posted on FR that some excremists were caught with a cache containing one or two TNT crates.
Much of what I've seen in these caches have been arty shells. The Navy had a really nasty accident involving stale dated bombs a few years before I enlisted. The old bombs didn't cause the accident, but made the situation far worse than it would have been otherwise. I may be a little overly paranoid about superannuated explosives.
The hardware would be OK. I think they should auction the AK's off here in the States, but, hey, that's just me.