I'm new to AR15.com so maybe this has been addressed. I don't mean to beat any dead horses here. just wondering how long is to long to keep mags loaded?

Short answer: Keeping magazines loaded is somewhat of a non-issue as far as weakening spring tension. The greatest weakening comes from use (loading, firing, then repeat). With that being said, some opt to load magazines 1-2 rounds short of full capacity to minimize possible weakening spring tension.

 

Keeping a magazine fully loaded for long periods of time will not have any effect whatsoever on the spring.

It will out live the owner.        but the spring weighs more compressed.  

No. Downloading is to make loading on a closed bolt easier.

I have a friend who is shooting up a mag of ammo a year of magazines he loaded in the mid 80's. They are all usgi and all were used when he loaded them.2 out of the 25 plus he has shot had issues years ago.

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That's what I do.....load 28 only.

This plus some of mine are going on 3 years loaded.

Except that it will. My Uncle passed me a mid 80's Beretta M92FS to figure out why it was stove piping. It had been fired "maybe" 300rnds through the 80's and then left in the case with the mags loaded for another 15 years. Upon receiving it I noticed the mags were feeding sluggishly. New Wolff springs and it ran like new. If it were only one mag I'd have said it was just a bad mag. But all 3?  Same issue?  Extended compression can have a negative affect IMHO...

+87

Agreed

The mags in the following pic were loaded a couple of years before the AWB sunset ... so around 2002 or so. I spot check them every spring and change out the desiccant. I have observed exactly zero issues:



When I spot check them, I grab a couple of mags at random and empty them with a LULA. Then I check the springs, floor plates, followers, feedlips etc. I then load them back up and put em back.

CJan-NH, do you SHOOT them? (not being judgmental, just curious)  I would think a visual inspection isn't going to tell you if they will function.

Just about everything I read on here says no harm keeping loaded and it is the cycling that makes them wear out, but I don't recall seeing any links to actual studies.  I'm sure Magpul or Okay has actually tested them (ie measure spring rates after compressing for several years, v. after x number of cycles of compression/relaxing).

I had some Sig magazine springs go bad and mainly from storage (got the gun and shot it a fair bit, then got away from shooting a few years before getting back, so they hadn't been used a whole lot).  Not sure if pistol springs are different composition? (like the post a few above about Berretta springs going bad from storage).

Anyone have any links to actual tests????

Here is a reference to a USGI test done in the 60's: link  Shows five years compressed decreased spring rate from around 5.5 to 4.6, but they functioned (m14) (and they had determined that 4.5 would be the lowest limit to "perform satisfactorily")

This shows some bad initial "set" but compared to a used spring not as bad as it looks in first pic: link


That is the best I can find searching for now....

The first link conlcluded that storage loaded does NOT effect them, yet the spring rate in 5 yrs dropped from 5.5 to 4.6, and it says 4.5 is the lowest they can expect to function.  I would guess that after 7?, 10? years the spring rate would drop down below the "functional" level of 4.5.  That test was done in the 60's and newer metals in the springs may make that test worthless for today's mags....


ETA: interesting in the first link (Springfield Armory) all the mags were within functional range after 6500 cycles, and 2/3 in range after 10,000 cycles.  They were cycling at almost 2 strokes/second!  That makes we really wonder about the "it's loading and unloading that wears out the springs" internet "fact"....  They only had a sample of three in each test, so certainly lots of room for statistical error, but interesting.

I am curious if PMags solved this issue and people are just going off the old GI mags?

Also, if you load a PMag to 30 and put the dust cover on it, it pushes the rounds down to a 30.5-31 load I think.  Does this matter?

And are there issues with the tabs deforming on the Pmags when the mag has 30 rounds?  This is why I use the dust cover, to prevent pushing on the top of the mag.  



Maybe all my thinking is wrong...  I might go to 28 rounds and a dust cover for storage.  And keep 1 ready to go w no cover.

That's funny, my cans are stacked with 5.56, .45, and 12g too. The old man used to tell me that's all I'll ever need.

Edit: response to Cjans pic, hit reply instead of quote.

I have 30 NHMTGs loaded with 28 rounds of IMI M855 that's been there since 2011.  I plan on shooting them one mag a year starting at ten years.  

I'll get back wit ya'll in 2021.

Well with the current market price of M855 I unloaded all those mags and sold the ammo this morning.

So much for science.

In the mid 2000s contractors found a bunch of loaded 20 rounders in the ceiling of an old Army barracks that was being remodeled.   LORD knows how long they were in there.    We fired all and had 0 issues; no spring failures and no feed lip spreading issues.

Head stamp would probably have offered a good clue.  Not exact,  but a good chance of being in the ball park.