As I was studying the array of gun safe options it hit me that I did not know the truth behind the hundreds of ammunition storage opinions that I have heard over the years. I have always just kept my ammunition in an Army surplus container and never encountered a problem.
The two most obvious environmental issues that effect ammunition are moisture versus heat. Does moisture weaken or compromise ammunition and can fire explode ammunition in a dangerous manner?
Some of the best information about the effect of fire on ammunition comes from firemen who enter into burning homes where a reasonable amount of ammunition is stored. The response is ‘yes’ ammunition will explode in a fire but the explosion is basically weak and rarely causes severe harm. I did find documentation that the weak explosion of ammunition in a fire is strong enough to damage a person’s eyes.
Most gun owners agree that storage of ammunition in a dry location is preferred as exposure to long-term moisture can damage to the casing. There are stories of people still using WWII ammunition and stories of using water soaked ammunition, but most policemen will tell you to simply keep your ammunition dry and in a safe location. There are a lot of opinions on these issues, but in the end it seems like it is wise to drain off your older ammunition in a good target practice session and if your ammunition is exposed to prolonged moisture think about replacing it.