There seems to be either a bug that when you stack a certain amount of ammo you lose a whole whack of it...
Once I bought a huge amount of ammo, I kept buying it just cause I was bored and thought I'd stock up. I had about 65K rounds in my inventory and bough another 20K rounds, when I merged the two, the ammo count went back to 6-7K rounds, as much as I could try, the rest of it had just dissappeared.
This happened to anyone else? And yes I realize it may seem idiotic to stock up on so much ammo, but hey, still shouldn't make it all dissapear just like that!