RE: AMMO Disposal
Can you post any pictures of the ammo or what the headstamps say?
Some old ammo is worth a lot of money.
As long as the cases aren't corroded, rifle or pistol ammunition will more often than not go 'bang' when you pull the trigger. I have shot thousands of rounds made in europe and the soviet union dated from the 1930s to 1970s with no problems other than a rare hangfire. If in doubt, clean the barrel with hot water after shooting in case its corrosively primed.
Paper shotgun shells- don't shoot these, not because of safety issues but because they are worth money. I doubt that any plastic hulled shotshells are old enough to cause any problems.