Folks are shooting ammo that dates back to WWII with no major problems. I think it mainly depends on how the ammo is stored. The G.I. stuff as you may know has been stored in bunkers (cool/dark environment). Your ammo should last a long time unless you store it in the trunk of your car or in an environment with large temperature fluctuations.
You can buy G.I. ammo cans from army surplus stores, or plastic ammo cans from some sporting goods stores for less than ten bucks each. Find a packaging/shipping specialist in the local phone book and ask them for silica gel packets, and you can store your ammo in airtight containers, free of moisture.
Or alternately, pack the ammo in zip-lock plastic freezer bags or the like, and toss in a couple of the silica gel packets. Use can put a strip of duct tape along the seal to make sure they don't open when moved around too if you wish.
[This message has been edited by LAK (edited 10-22-2001).]