So, do you think keeping the magazine loaded will weaken the spring over time? I'm only wondering this, because I want to keep the gun easily available for any emergency in my home. I will keep it on a closet shelf just outside my bedroom.Magazines springs may be cheap and you may not worry about them but they absolutely can stop a pistol from feeding.
The springs under your car are not compressed to their working limit and then held fully compressed for long periods of time.
Double stack mags will weaken from storing fully compressed. Single stacks - not so much.
Maybe not the springs UNDER your car, but what about the springs IN your car? Valve springs, specifically. I've NEVER heard of valve springs failing because the engine was shut off and an intake or exhaust valve was fully open (=spring full compressed). I'd wager that valve springs are placed under thousands of times as much stress as a magazine spring is, too.
Valve springs are compressed around no more than about 1/2" and the spring itself is around 2" or maybe more.
So we're talking that its compressed only roughly 25% of its length.
Mag springs are compressed substantially more than that.
An engine turning 2000 RPM's for just 1 hour compresses the valve spring 120,000 times.
Ive got well over 3000 hrs on my truck motor. Each valve spring has seen well over 360 million compression cycles.
By that analogy, a 10 round mag spring should last 360 million rounds over 10 years while being stored loaded over each night and still be going strong.
I'm going to hold firm that there's more to it than just compression cycles that degrades springs.
Until someone can post scientific evidence (instead of anecdotal or common belief) stating that static loading will progressively weaken the spring, I will continue to assert that spring fatigue is a function of cycling between being loaded and unloaded.
Here some info that shows springs in a static compression does have a negative effect.
Ive posted lots of data on THR and TFL.
Oddly, people that claim that static compression has NO/ZERO impact impact on springs has ever, to my knowledge, provided any test data to support their claim.
This 1st has data at only 200 degrees.
http://www.spring-makers-resource.net/support-files/fig_37.pdf
http://www.spring-makers-resource.net/spring-designs.html
http://www.spring-makers-resource.net/compression-spring-design.html
http://www.mechrel.com/articles/Mechanical-Spring-Failure-Modes/
The myth is not a myth. Contant compression does affect springs.
How much will be determined by the overall design.
But rest assured, nothing lasts forever. Not even a spring.
In fact, check this out: http://www.efunda.com/DesignStandards/springs/calc_comp_fatigue_eqn.cfm
According to that website, which gives equations on calculating spring fatigue, it states that, "By definition, objects that are loaded under purely oscillatory loads fail when their stresses reach the material's fatigue limit. Conversely, objects that are loaded under purely static loads fail when their stresses reach the material's yield limit."
By that definition, if a spring were going to fail from a static load, it would do so the first time you loaded a magazine because the force would be enough to physically deform the spring enough so that it would not spring back to shape. (http://en.wikipedia.org/wiki/Yield_(engineering))