monern ammo has a life of several years Last year I used some 9 year old
.243 worked good B.J.

 

Well, my son and I just finished last month about 150 rounds of WWII 30.06 ammo that my father had given me years ago. It was pretty hot loads, but each and every one fired fine. And yes, it WAS authentic...

So with that being said, I would say as long as it stays dry, it will last a long time.

As always, Stay Safe.

 

There have been lots of people who have found 40 year old ammo, or more, and it fired just like it should have...

 

I have some .22 ammo that is around 20-25 years old. (packed it away and forgot it was there). I've shot some of it and it works like a champ.

As far as telling how old ammo is, maybe look for clues in the lot numbers on the box.

 

Theres really nothing in a round that "Expires" as long as its kept properly... As long as it doesn't tarnish horribly or get very wet...