Ammo will go bad over time. I've got a couple of coffee cans of 12 guage that I inherited from my Uncle. These shells are ancient, (I'm guessing back to the 50's). Last summer, I had a racoon that enjoyed my garbage at least one a week. One night, I heard him tipping my cans over and told my wife, "tonight is the night!" I grabbed my gun and one of these shells, went outside and sure enough, there he was chowing down. He ran up to the top of an oak tree that sits next to my garage. I got right under him, aimed and pulled the trigger. The gun gave a soft "pop," the shot came out of the end of the barrel and literally rained down on top of me. I don't think it went higher than 10 feet in the air. Oddly enough, the racoon never returned. I think he was insulted at the way I had tried to kill him.