Didn’t shoot it all? Bury it!
One common thing that happens all the time in the military is being issued too much ammo, such as on a live fire exercise, and intead of returning it which is a whole pain in the ass, it gets disposed of via E-tool.
Well apparently in 1945 when a B-24 unit was leaving England to return home, they left a few belts of .50 cal behind in the dirt of their borrowed RAF airstrip. Fast forward 70~ years and some aviation buffs dug up about 1,500 rounds of still very live tracer and ball ammo just three feet below the surface.
Heck, I am surprised they didn’t find a whole B-24!