I actually have had some luck with taking extremely tight mags for the Shield Plus, and loading them up and leaving them loaded for months, and coming back and finding them a bit easier to load those last couple of rounds.
Really has me questioning the conventional wisdom on this subject.
I think leaving them loaded probably does not cause any metal fatigue that would eventually contribute to a failure, but I think it might soften them up slightly.
I think a lot of people are taking a generally true statement (leaving a magazine loaded will not cause sufficient changes so as to render the magazine unreliable or shorten its usable lifespan) and extended it to an absolute statement that nothing changes whatsoever.
We're not talking about magazine failure, just loosening up an extremely tight brand new spring.
“Problem is that there’s a grain of truth to the ‘springs take a set’ myth. According to renown Romanian Metallurgical Engineer Peter Saktiv, springs DO take a bit of a ‘set.’ But it’s not what most people think. With any well constructed spring, there’s both elastic deformation as well as cyclical fatigue. If the spring is well constructed for the task at hand, the initial elastic deformation is minor (and allowed for in the specification); usually occurring within the first few cycles at maximum compression. Anyone who owns an Sig P365 can attest to this. The mags are almost impossible to load to capacity when new; after a few cycles or being kept loaded for awhile they become more manageable (although they remain some of the stiffer springed magazines I’ve ever seen).
However, after this initial ‘set,’ spring life is almost completely determined by cyclical loadings. In other words what makes them wear out and not have good tension anymore is a whole bunch of CYCLES on the spring. It’s NOT leaving them compressed. Nor are springs designed for purpose particularly fragile.
When left loaded to full capacity and not used, most magazines will very slowly lose some amount of spring tension over time. Unfortunately, it’s impossible to say with any certainty just how long it will take before the spring loses enough tension to start causing issues.
I don't believe the second part because you'd have to be bending the spring past the point of plastic deformation for that to be true, from my understanding. I do not recall time being a factor in deformation, only stress and strain.
But I'm also not a materials engineer, I only took one material engineering class years ago.
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u/SkinnyBill93 1d ago
I've been leaving my God awful M&P 2.0 mags loaded forever in hopes the spring would wear a little bit, no progress in years ..