My pistol mags are full to the top with one in the pipe. My standard-capacity AK and AR mags are loaded to 29 rounds each. It is easier to load them on a closed bolt for competition. I didn't drink the Kool-Aid; I just am lazy. ![[wink]](/xen/styles/default/xenforo/smilies.vb/002.gif "Wink [wink]")
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True or myth?
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The problem isn't the cost of the replacement mag spring but when the original spring fails. I believe that these springs will last longer when stored in the relaxed position, rather than fully loaded/compressed.
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When was the last time the you had (or even heard of) a magazine spring fail?
Springs don't fail because they are compressed. Springs fail due to metal fatigue. Metal fatigue is caused by movement, not static load. Loading and unloading your magazines requires movement, which may create fatigue. If it has any affect at all (which is unlikely), "rotating" your magazines does more harm than good, because rotating them increases the number of loading and unloading cycles.
This is one of those myths that people keep repeating but don't have any evidence (or understandable theory) to back up.
dcmdon
NES Member
I don't think anyone would argue that in a relaxed state they will ultimately last longer.
I store most of my mags empty for the reasons you stated.
But I think nothing of keeping "plenty" of them fully loaded. All my pre-ban mags have new wolf springs in them anyway. So its nothing to keep them filled.
With that said, most of my pre-bans are downloaded by 1 or 2 rounds just to make it easier for my wife to insert a mag on closed slide/bolt. She also has a tendency to ride the slide forward. Leaving a couple out makes the gun more forgiving of that error.
Don
When it flew across the room and I stepped on it trying to find it.![[smile]](/xen/styles/default/xenforo/smilies.vb/001.gif "Smile [smile]")
It didn't wind up underneath something very heavy, just beyond reach? I thought they were carefully engineered to do that.
![[laugh]](/xen/styles/default/xenforo/smilies.vb/012.gif "Laugh [laugh]")
I am no expert, but I believe that "metal fatigue" and loss of tension are two different problems. Constant flexing can cause fatigue, particularly in metals not designed for this flexing. A fully compressed mag spring may lose its tension simply because it is held in the compressed position for an extended period of time, i.e. years.
Loading and unloading the mags should have absolutely no ill effects on these springs as this is what they are designed for. This is also the function they perform when firing the pistol. I have yet to hear of mag springs that fail do to over use. Unloading your mags and rotating the ones you keep fully loaded is cheap insurance. It requires very little effort and can do no harm.
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KMM696
NES Member
You are right, you are no expert. Did you ever study strength of materials in college? Because it appears that you do not understand fatigue or the behavior of steel.
So, do you put your car up on jacks every night to take the weight off of the springs? No? And yet after years of being compressed, your cars springs still aren't sagging.
I've got AR magazines in my safe that have been loaded for 15 years. I've got 1911 mags that have been loaded for more than 5 years. I've got Glock mags that have been loaded for more than 15 years. I bet you $50 that if you meet me at Harvard Sportsmen's, they all work without failure.
Oh come on. Just stop it. Please.
If steel isn't loaded beyond its yield strength, then it won't suffer plastic deformation. And the load caused a mag spring is tiny.
Magazine lips get damaged because they get smacked into things, typically the magazine well on a botched reload or dropped on a concrete floor.
Every once in a while a letter shows up in one of the gun mags that someone found grandpa's 45 auto with loaded mags brought home from WW 1. They take the gun out to shoot it thinking the magazines and ammo are no good being loaded for 100 years ago and are surprised that the gun fires and the magazines work like the day they were made. That what gave JMB his reputation as a firearms genius the simple fact that his designs always worked no matter what.
dcmdon
NES Member
If steel is flexed within limits, it does not accumulate fatigue. In other words if a spring is designed properly its life is infinite.
This is in contrast to aluminum, which accumulates all fatigue. In theory, you could break a solid 3" aluminum bar with your two hands, if you had enough time.
dcmdon
NES Member
This has been a chronic problem with PLASTIC magazines. Thats why Magpul developed that cover to snap over the top of their mags when loaded. Its never been a problem in metal mags, as long as they are designed properly.
A lot of new pmags don't come with the dust cover.
dcmdon
NES Member
Yup. They did that to increase production capacity. They also only made black mags during the height of the panic. I don't know if they've made improvements to allow them to be stored without the covers.
One other thing re storing Saiga 12 mags loaded.
In this case, the plastic shotgun shells will deform over time if left in a Saiga mag. Particularly the top shell. I'm deviating a bit from the original question, but just thought I'd throw this out.
Does anyone have a link to a statement from Magpul about it, either saying that they recommend using the covers or that it doesn't matter, anything? Always take what a manufacturer says about their product with a grain of salt, but I'm curious.
For what it's worth, I've had a feed lip break off of a Gen2 PMAG. I'm not prone to storing them long term without the clippy things... it did brake right after I cam back from Iraq, so it took quite a beating before it broke.
We're moving way off the main point here though.
MYTH; mega, evil, super MYTH that must be cleansed from this world by the internet equivalent of atomic fire.
dcmdon
NES Member
Back about 3 or 4 years ago, I remember reading a magpul statement saying the covers were solely to protect against dust.
However, if you have ever used one, its obvious that part of its design function is to take pressure off the feed lips, since it depresses the ammo column by about 1/8".
That doesn't necessary mean its necessary.
However, if you have ever used one, its obvious that part of its design function is to take pressure off the feed lips, since it depresses the ammo column by about 1/8".
That doesn't necessary mean its necessary.
Scarecrow
Army Veteran
My $.02:
Isn't it weird how a car's coil over shocks occasionally wear out when they are driven for many many miles with heavy loads, as a work truck occasionally does... yet people find cars that have been sitting in barns for 60+years and the springs are still perfectly fine?
Compressing and releasing does damage, holding the springs static doesn't hurt them at all, it is what they are designed for.
Isn't it weird how a car's coil over shocks occasionally wear out when they are driven for many many miles with heavy loads, as a work truck occasionally does... yet people find cars that have been sitting in barns for 60+years and the springs are still perfectly fine?
Compressing and releasing does damage, holding the springs static doesn't hurt them at all, it is what they are designed for.
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One step further - valve springs. Have you ever had to replace your valve springs? How many cycles do they go through... per second?
Again, it goes back to cycling (i.e. movement or deformation) and the magnitude of the deformation.
What do automotive shock coils and valve springs have in common that make them perform so well over and over again? A high ratio of coil diameter to length of cycle. Hefty coils that don't have to "spring" that much wont develop as much fatigue over time. Mag springs on the other hand, like mattress springs, are mincy thin springs that - relative to their coil thickness - deform a fair bit during cycling leading to greater fatigue. All things being equal, the greater deformation leads to more numerous cracks in the microstructure leading to fatigue exacerbated by a thin cross section of coil.
Again, it goes back to cycling (i.e. movement or deformation) and the magnitude of the deformation.
What do automotive shock coils and valve springs have in common that make them perform so well over and over again? A high ratio of coil diameter to length of cycle. Hefty coils that don't have to "spring" that much wont develop as much fatigue over time. Mag springs on the other hand, like mattress springs, are mincy thin springs that - relative to their coil thickness - deform a fair bit during cycling leading to greater fatigue. All things being equal, the greater deformation leads to more numerous cracks in the microstructure leading to fatigue exacerbated by a thin cross section of coil.
Correct. Weird though, I've seen new windowed ones and they still didn't come with dust covers. Maybe magpul still hasn't caught up to production ?
dcmdon
NES Member
Pure speculation. But I'm guessing they've done some market research and found that most people don't care. I have some Gen 1 Pmags and have lost all of the covers. The Gen1 Pmags didn't allow you to store the cover on the base of the mag. So they just floated around in rifle bags until they got lost.
For what Its worth. I've got beater mags and I've got mags for matches. The match mags are stored empty and cleaned every few uses. It may do nothing, but it can't hurt.
I have no formal education in metal fatigue, but I do have a bit of common sense. Leaving a mag loaded for fifteen years simply makes no sense. Why tempt fate?
Your use of automobile suspension springs as an example makes no sense whatsoever. When the vehicle is at rest, the springs do support its weight, but they are only partially compressed. When a magazine is fully loaded its spring is completely compressed, unlike a motor vehicle spring which is only partially compressed. Finally, motor vehicle suspension springs do wear out and vehicles do sag, requiring spring replacement. How do I know? I have replaced them on several occasions.
What is fully compressed? What is partially compressed? It all depends upon the design of the spring. As long as the spring isn't compressed to the point of plastic deformation, then it will return to its original shape when unloaded.
The car analogy actually is an apt one. In both cases the springs are under constant load. Constant load doesn't break springs, provided that load is within the springs design limits. What causes car springs to break or sag? Being overloaded and/or many compression/extension cycles is what wears out springs. Your car just sitting in the driveway on its springs doesn't wear them out.
Once again, I'm not risking anything by leaving mags loaded for years. Compressing and extending springs over and over by loading and unloading springs is what wears out springs.
I'll make my offer again - $50 says my mags that have been loaded for more than 10 years still work.
dcmdon
NES Member
There is no such thing as "partially compressed" and "Fully compressed". Either the metal deforms plasticly or not, and fatigue is a function of the number of times something has been flexed.
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