Cases man, not boxes!
SKS's eat ammo like candy. I'll blow through what I have on strippers and then say "OK, all done." Then I'll find a couple of strippers with just a few rounds on them and say "What the hell, I'll quit after these."
THEN I'll find a couple of loose rounds in the ammo box... "Fuck! Ok, I'll quit after THESE are gone."
THEN I'll find a couple of loose rounds in my pocket.. "OK, I SWEAR I'll quit after these are gone."
It's just that kind of fun.