About as long as the heller decision it seems.....
http://www.foxnews.com/story/0,2933,377203,00.html
Honestly I have factory ammo from the mid 30’s and 40’s that has functioned perfectly.
Proper storage is the key ! A food save and a chest type freezer keeps 02 and light out of the formula as well as temperature stability ......leave the chest type freezer unplugged ! I store reloading components , powder and primer in this fashion and all is in good condition !
As well date and time group aka DTG the packages you make with the boxes of ammo in the original boxes wrapped in the vacuumed food saver bags with a sharpe marker .........
That is best way a civilian can store ammo IMO and experience !
Always enjoy trading verbiage with ya Dave !
Stay safe !
This you tube link has an excellent discussion of what many of us have discussed here on Free Republican:
http://www.youtube.com/watch?v=03_ZHGAJxSQ&NR=1