I would like to know if PMC ammo is good for long term storage(5to10years). The catriges are not sealed(they won't be under water either.

Clearly, some ammo is better than others, such as those with sealed primers and bullets. But any new production ammo would be fine for long term storage in that if you store them correctly they will be good for many, many years to come.

However, For what reason are you storing it? PMC isn't really a good storage ammo in that it isnt really suited for anything other than reliable range use. If it is to be stored for "social" use, it is a poor selection based on its weak terminal performance.

I have had trouble with PMC in my Bushmaster, and when I posted the problem, at least one other poster commented on the same issue.

The copper is soft on the bullets, and builds up  when smearing on the feed ramps.  After a dozen rounds or so, the bullets start to "stick" on their way into the chamber, sometimes jamming, sometimes just making the rifle buck as it feeds, sticks, and gets loose.

Secondly, if you are saving it for defense, PMC isn't nearly as powerful as Lake City or Winchester Q131A.

If you are going to store ammo, get some Lake City M193 or Winchester Q131A from an on-line source or local store.  I've heard here that lake City Lot6 and Lot7 aren't sealed, but I've got a ton of Lot 1 and it's great stuff.

PMC ammo, if properly stored will last as long as any other commercially available ammo, but the key word here is properly stored.
I don't think there is much disparity between federal XM193 and federal American eagle ammo other than the military designation and the color of the box.

weaksauce, your kungfu is weak and no match for the ammo oracle's shaolin, please read.

www.ammo-oracle.com