I've got a bunch of circa 1937 Kynoch 7x57 Mauser that was sealed up in a thousand round spam can and unopened until 2012. The stuff looks like it was made yesterday and this past summer I just had to chrono some because it all goes bang and is pretty accurate out of an old 1908 Brazilian Mauser with visible wear in the barrel. It averaged 2877 fps (140 gr. bullet) with an extreme spread of 51.7 fps at 68 degrees F..So I imagine that under proper storage conditions most any well made ammo is gonna last a lot longer than we usually think.
