Few years ago I found 144 (gross) 7.62x54R rounds abandoned.
Pulled a bullet from one and found this:
View attachment 1181026
Bullet jacket was copper plated steel, hollow base rusted, gunpowder clumped in the case neck but granular past the clump. Pulled nine more bulets from cases at random from the bag. The primed cases refused to fire in my Mosin Type 53 which made a healthy indent in the primers.
I ended up with 144 bullets in the trash, 144 brass casings for metal recycler, and a peanut butter jar full of unknown compromised acidic powder (which made an impressive orange flame in the burn pit on the mountain one damp afternoon).