Wanna know what keeps me up at night?
Not knowing whether the the loot from each chest is pre-determined when you start the game....
...or if it’s always changing—if you open a chest 1s later, will you get different loot than if you were to open it 2s later?
No one knows! 
Most likely it's calculated when you actually open the chest. Saving data for each chest and ammo box on the map would waste so much storage.
