Quote Originally Posted by SHTF View Post
When I served in army back in 91-93 we were told that spring is getting weak after being compressed for a long period of time. I don't know if springs are different now but I still play it safe and rotate loaded mags once a week.
Maybe if they are over-compressed, but a spring only wears out from being worked back and forth.

To demonstrate - take a metal paper clip and unfold one of the bends. The metal will have the same springiness to it unfolded as it did folded. Now, bend the metal back and forth. It will get warm at the bend and eventually break. Before it breaks then resistance to bending will be much less.

The military has a bunch of old wive's tale policies and beliefs that have gotten passed down from isolated incidences. The only one that I can remember that holds true is when keeping a fulling loaded M16/M4 magazines in the gun. There usually isn't enough play left in the magazine for the 30th round to sit up against a closed bolt - it over compresses the spring, which can wear it out. Thus why some branches or drill instructors teach you to old load 29rds into the mag with a closed bolt or to have the bolt locked open when carrying a fully loaded magazine in the gun.