I have made a screenshot where you can see that I have got a negative Ammo Display --> pls check uploaded picture
This has happend so:
Using a M16A1 costs 4 Ammo per shot.
I was running out of ammo and my last fillment did not fill up the whole magazine.
I got only 38 bullets.
I guess that software checks only against AMMO > 0 but not against AMMO >= NEEDED AMMO PER SHOT
This bug could be easily fixed ...