Paul,
Colt45 is right. The way we store them is with the bolt closed and the hammer down. That takes all the tension off the buffer spring and the hammer spring. If you want to get an AR and learn alot about them and save money, your best bet is to build one. It's alot cheaper and you can build it just the way you want it. When your finished you will be squared away on AR knowledge. While building, if you run into any problems you have this forum or you can order one of the books or videos, it really is easy. Good Shooting! Eric