If kept dry and clean it will outlast you. I shoot .45 ACP that has '42-'44 headstamps. I have shot a pile of it and have only had a couple of failures to fire. I have a feeling they would have failed to fire in '42 or '44 too.
Loaded, quality, magazines will remain functional for years as well. It is a myth that the springs take a set after a short time.
Any weapon used for self defense should be shot often enough to cycle through magazines and ammo, but I would not be concerned about "shelf life".
All that said, I did forget about a case of shotgun shells that I put in my barn for about five years. I live in Florida where heat and humidity is a serious issue. When I found them, I took out a couple of boxes that showed signs of weathering and sure enough I had enough failures to mark all of the boxes for only practice use.
"It is better to be too skeptical then too credulous"
Last edited by Chainfire; 12-30-2011 at 08:50 PM.