I've bought lots of ammo. I'm not worried about range ammo that's a few years, or even a few decades, old, but I do rotate defensive ammo out regularly.
My stockpiling has more to do with avoiding the impact of future price swings on my hobby.
In 2013, you couldn't find 5.56 for under $1.00 a round. I've bought a bunch of good quality (brass, annealed, lacquered, mil spec) 5.56 recently for $0.28/round.
Ammo is very cheap right now, if I could've stockpiled gasoline when it was $1.29/gallon in 2001, it sure would've been nice in those days, just a few years later, when it hit $4.00/gallon.
OP, go ahead and shoot the ammo. You'll be fine.