I've only fired 120 rounds of mine, but so far, so good.
The ammo was manufactured in the early 80's, but comes packaged as well as you can imagine: wooden crate, 200rds in 20rd boxes in each of the 5 heavy-duty (MRE-like) plastic "battle paks (their words)." Each round appears to be sealed with blue/green varnish.
My favorite part of the packaging was at the bottom of the label on the wooden crate: "Keep out of reach of children."
That's the one thing missing from the nuclear bomb that Sideshow Bob stole in the Simpsons.