Although I do shoot up my carry ammo after a year or so and put in fresh, I have NEVER EVER had a "vintage" round fail to fire. I hunt with Shot Shells inherited from my Dad, some of which are paper hulls and must be at least 65 or so years old. They never fail!

I also fired some .45 acp rounds that were loaded into 3 1911 WWll vintage GI Mag's. I do not know how old the ammo was but it did have the dome shaped primers so I am assuming it was at least from the 1950's. All worked perfectly and I do not even know how or where they were stored or carried.

Just to err on the side of caution it's not a bad idea to rotate out ammo after a year or so and if nothing else it gets you to fore your Service Rounds for practice!