George: For starters, let me say that I’ve been hunting with .270, .30-06 and 7mm loads from a test batch I got at least 10 years old. Some of the cartridges are 15 years old.They are still reliable and accurate, and I’ve killed dozens of bucks with them.
If center-fire cartridges are stored in a dry place at moderate temperatures with low humidity—say on a shelf in a dry basement where you have a dehumidifier running—they can have an amazingly long shelf life. There are many reports of people shooting 50-plus year-old ammunition with no problems, and killing deer with such ancient rounds.
But before shooting any old cartridges, check each one carefully. If the cases look clean and aren’t corroded, the ammo should work fine. But keep in mind the warning signs of unusable (and potentially unsafe) old ammunition: split case necks and/or corroded/rusty bullets, brass or primers. If ammo shows any of these signs, discard it properly and don’t shoot it.
DISCLAIMER: If you have the slightest doubt that a round or bullet does not look right, discard it and don’t shoot it.
Probably the best and smartest thing to do with shells left over from the last few seasons is to go the range this spring and shoot them up. Then go buy a couple new boxes of your favorite deer load before next season. The ammo companies will appreciate it, plus you’ll benefit from the shooting practice. You’ll know those shiny new rounds to be safe and effective.