Springs lose their tension as a result of being compressed and released. You won't damage springs by leaving them compressed, as long as you don't compress them past their design limit. If the springs rust, that's another situation. I know of some inherited .45 magazines that belonged to a friends' uncle. (WWII vintage) The outside of the mags were badly rusted, but the rounds popped out, and the follower did its think just like it was supposed to. Best I know those mags are still being used.
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Freedom has a flavor the protected can never taste...
USMC 8652, 2531, RVN Jun '67, - May 69
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