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Is it OK to carry a loaded magazine for months at a time or is it better to alternate 2 magazines so the spring can relax occasionally?  Or, plan C, load just 4 or 5 shells so the spring isn't fully compressed.  Thanks.
 

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Wilson said:
...as flexing the spring is what weakens it.
Isn't the basic purpose of a spring, to flex? Isn't it designed to do just that?

In any event, the question was posed in the NRA magazine American Rifleman quite a few years ago by, I think, a police officer. As a member since '76 I usually abide by the NRA's recommendations. And they went something like this: use 3 magazines. Two are loaded fully, the last is empty. A loaded one in the pistol, another is a spare. Every six months or so, fire the ammo in the pistol. Replace with the spare. Let the fired mag rest. Load up the one that was resting for 6 months as the spare. Keep rotating your mags as you would tires on your car; each gets the same amount of wear over its lifetime.

Seemed like good advise at the time and I still abide by it.
 

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The flexing of the spring is what fatigues the metal, not that actual compression. There have been many debates on this topic on this board over the past year. Most of the available data has bolstered my first statement. So in other words, your mags that you are rotating are actually being worn out. They are being rested when you are actually leaving them alone, loaded or unloaded.

An example would be a truck's leaf springs. You can leave a pick-up truck loaded with 500 pounds and leave it parked for years. The leaf springs will never go bad or wear-out. What wears them out is the constant compression and decompression while the truck is being driven. It's simple physics.
 

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Or your mattress!

Is it the constant flexing, or the weight on it that wears it out?

Mattress companies use a machine to flex an innerspring mattress until the springs wear out to test its lifespan.

It would be far cheaper for them to just put a couple bags of sand on it and come back later.
But nothing would have changed!

(You thought I was going somewhere else with that didn't you!) ;D


rcmodel
 

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From all I've read from those who know about the subject , "resting" magazine springs by unloading them and letting them sit for awhile does nothing. As mentioned, it is the compressing/uncompressing that fatigues the spring.
 

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I have read that - rotating the magazines you CARRY is a good idea - the motion of a person moving - can cause the cartridges to move / rotate and it may cause the mag to jam up. This will not happen in a few days - but imagine a cop walking a beat every day for a few months.

Many police are trained to rotate their mags as a result.

There were also many magazine failures in Vietnam - that were BLAMED on leaving the mag fully loaded - the Army studied it - and determined that the magazines - designed to hold 20 rounds - could - with a little effort hold 21 rounds - they were using bulk packed ammo - so it was easy to miss count - and end up with 21 rounds in a 20 round mag - the extra force could cause the first round to jam - for a while the Army procedure was to load 18 (in a 20 round mag) - once they figured out what the real problem was they started using a stripper clip that held 10 rounds - so 2 clips = 20 rounds.

For years I always stored my mags with 1 or 2 less rounds than capacity and NEVER HAD a problem.

Then after reading some of the posts on KTOG and some research - I made a change - loaded up all my mags to capacity. Some sat for a few months fully loaded - and when I took them to the range - the result was JAM JAM JAM -

This could have (most likely was) just a coincedence - but since then I have taken one round out - and have not had any problems. All in my head - but your head pretty important - and it does not cost me much to load them this way.
 

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z71bill said:
There were also many magazine failures in Vietnam - that were BLAMED  on leaving the mag fully loaded - the Army studied it - and determined that the magazines - designed to hold 20 rounds - could - with a little effort  hold 21 rounds - they were using bulk packed ammo - so it was easy to miss count - and end up with  21 rounds in a 20 round mag - the extra force could cause the first round to jam - for a while the Army procedure was to load 18 (in a 20 round mag) - once they figured out what the real problem was they started using a stripper clip that held 10 rounds - so 2 clips = 20 rounds.
 
That's a different issue and I understand there is validity to it, overloading a magazine or fully loading double stack magazines for extended periods. That can be a problem.

It's not supposed to be an issue with most single stack magazine but I do typically download by one round on the magazines I leave loaded for extended periods of time just in case.
 

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The problem with loading 21 rounds in a 20 round (or 31 in a 30) M-16 mag is not spring fatigue.

The problem is, you can't lock one in a rifle with the bolt foreword.
It won't lock in because there is no more compression left, and the top round has to squash down slightly, or the mag won't go in the rifle.

The jams, or more correctly, hang-ups, were because the 21 rounds are stuffed so tight in the mag, the bolt carrier doesn't have enough power to strip out the top round when the bolt is released.

It didn't hurt the spring in the least, but it could easily get you killed in a fire-fight.


rcmodel
 

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rcmodel

I agree - but loading the mag full got the BLAME - even if it was not the true cause - its like so many things - a real problem (jamming 21 rounds in a 20 round mag) causes a jam  - the solution - only putting in 18 rounds in solves the problem - so everyone just thinks that it is bad to fully load up a mag. Once the bad infomation gets out - it is hard to change.  

Same thing with putting the magazine spring in the wrong way - in some cases it still works - but in others the last 1-2 rounds may not feed.

So how many guys have tested a new mag a few times to make sure it works - then cleaned it - (put the spring in wrong) loaded it up and stuck it on a shelf for a year or so - then took it to the range and had the last 2 rounds NOT FEED! They know the mag worked before they left it stored fully load - and it just seems right - that when the last 2 rounds don't feed it is because your spring is weak - so the the BLAME goes to filling up the mag.

I admit that it most likely makes no difference if you fully load and store a mag. But

I still have a small doubt - I even measured the mag space on my 40 caliber (after my mag failure) - when fully loaded - and counting the space under the follower the spring is smashed down to less than 5/8 of an inch. Seems pretty tight - even less than the mag on a P-3AT.
 

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"to measure is to Know"-- Lord Kelvin

the magazine spring has a wire diameter of 0.035".
there are 12 coils
the solid height would be 0.42

the inside space in the follower is 0.42, so the spring goes solid at the same time the follower touches the inner plate

with 6 rounds in the magazine, the follower is 0.23" from bottoming.  you should be able to push the top of the last round down so the rim is flush with the notch in the back of the magazine.

when pushing the rounds down the last 0.040"to check above, I can feel the spring jump a coil (requiring just a little more force)

when installing a fully loaded magazine, the rounds are pushed down 0.180", thus the spring is just 0.050" from solid and at the point I feel the slighty coil jump.
 
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