On Magazine Springs

SayUncle notes that someone is going to try an experiment, in regards to whether keeping magazine spring loaded causes them to wear faster. I should note that from engineering principles, there is no doubt that a loaded magazine will wear faster than an empty one, but the question of whether we’re speaking short time scales, such as 13 years, is another matter. I’d be willing to be your time scales here are on the scale of decades.

My feeling, just based on some things I know about springs, is that magazines which get used regularly are going to wear the fastest. Cyclic compression is the most fatiguing to the metal in a spring. Extended periods, even at full, static compression are going to be less fatiguing than if you were unloading the magazine every day.

If I had to bet, the magazine that’s been loaded for 13 years works just fine. At least not much worse than a magazine that’s been empty for 13 years. Time wears on springs too, whether you compress them or not. My feeling is that it’s probably best to leave magazines seldom used unloaded, but it’s far better to leave a magazine loaded, rather than loading it and unloading it regularly.

7 thoughts on “On Magazine Springs”

  1. Depends on the spring design. Cyclic compression will fatigue almost all the springs, but a poor spring design may be weakened by overstress or perhaps creep just by over compression.

  2. It is my understanding that keeping a magazine spring compressed for long periods will not harm the spring: it is compression and release cycles that wear them out.

    Besides, magazines are semi-consumable items are they not? Use them until they no longer work reliably, and then get new ones.

  3. cyclic compression is the most fatiguing to the metal in a spring.

    I’m willing to assume that’s true (not having studied it very deeply).

    My impression is that if magazine springs fail either from cycling or from mere compression, it’s because the spring was badly spec’d.

    My evidence for this is that it is certainly possible to make a spring that will survive millions (billions?) of cycles of compression and decompression, furthermore at very high temperatures, and do so for decades.

    Valve springs in cars typically last the life of the engine, are exposed to exhaust gas in the thousand degree range.

    Naturally they’re rather different from magazine springs, in weight, thickness, and duty cycle – but they do prove a point about potential durability.

    It may be that it’s not worth the extra weight and expense to have a “lifetime” spring in a magazine, since feed-lip and locking wear, or other damage, might make it a bad trade-off, commercially.

    But it certainly ought not be impossible to manage, or really all that difficult.

  4. The problem that arose in the military was that magazines for the M14 and M16 were not given much thought. The logistics of having that many magazines and life cycles was just not thought through. I joined in 1986 and magazines were the limiting factor of the weapon. The older sergeants would stomp a bad magazine and have the soldier turn it in for replacement. That was the only justifiable reason to get a replacement (damage). If you attempted to turn in a magazine that did not work, the system would kick it back. The supply sergeants were given guidance that each soldier need to have 7 magazines (working or not).

    As we fought a few more wars (or whatever we call them) and young soldiers became policy-makers, magazine have become an easily replaced commodity. When we deployed in 2009, we were issued new (still in individual airtight bags) magazines for both rifles and pistols. Some of us also bought PMAGs for a personal use.

    The point being, magazines are replacable. The misconception is that originally it was assumed magazines were part of the weapon and would last until…. Magazines are like car tires. They need to replaced at intervals. Each manufacturer will have to attest to the interval.

  5. For what it’s worth, about a dozen years The Gun Digest had a small article by Bob Bell (one of their fine perennial contributors) about a loaded 1911 magazine that he brought home with him from WWII. He kept it loaded with GI hardball ammo that he had carried with him during the war. After about 50 years he finally decided to shoot the magazine and expected it to fail. He found instead a perfectly functioning magazine and seven cartridges that all fired without a hitch. So your notion that a compressed magazine won’t fatigue is most likely correct.

  6. “Spring compression” of magazines stored loaded for a prolonged period is a common gunstore commando myth.

    Several years ago, Joe Waldron (COL, USMC, RET) related a tale on he WA-CCW yahoo! group about cleaning out an arms room; there were several lockers full of loaded magazines, for, IIRC, M14s, BARS, M3 Grease Guns, and M1911s. From the vintage of the weapons, you can assume that they had been loaded for a long time.

    They all functioned perfectly well.

  7. Being fully loaded will only cause the spring to fail if the magazine is poorly designed. A steel spring can be compressed, and left that way, indefinitely as long as the stress caused does not exceed the elastic limit.

    This is first week stuff in an engineering fatigue class.

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