In Survival Mode, ammunition is in short supply. If you find yourself needing more, look for an ammo cache. Ammo caches are time-limited stores of ammunition that can be found around the map. When an ammo cache becomes available, its location is indicated on screen by a yellow dot labeled Ammo. Once used, the next ammo cache won’t appear for a short amount of time, so try and use your ammo conservatively and keep your accuracy high.