There are 4 different types of ammunition that exist in TABZ: .50 Ammo, Shotgun shells, Medium ammo and Small ammo. Ammunition can be found just about anywhere, from stray houses to the Military Base, and can also be sometimes dropped from Zombies. Collected just like weapons, they will give a set amount of ammunition depending on which type you collect. Ammunition boxes collected from dead players will give you all the ammo they had (of that type) in one box. There doesn't appear to be a limit to how much ammunition you can carry at once.