I have always, unloaded my magazines in hunting rifles, thinking leaving ammo in will weaken the spring being under pressure all the time. I CC revolvers, but lately I’ve been picking up a few semi autos, I have a couple bodyguards, and a shield 45. Is there any truth to my line of thought, of unloading magazines for the sale of the spring? I would like to start carry these more, or leave them in the end table next to my bed, but kind of a pain to unload magazines all the time. Just thought I’d ask some guys that know.
Magazine springs
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kthom
Member
Unloading/unloading your mags often actually exercises the springs more than is likely with shooting unless you do that very often and a lot. It is the exercising of the springs (compression and derompression) that eventually weakens them. Leave your mags loaded without concern. Any mag I expect to use anytime in the not too distant future remains loaded. Most of the time, if I unload a mag, it is done so by shooting. When you are done shooting, you can leave them unloaded or not (until you get ready to go shooting again. For my mags in a carry gun, I will shoot the carry ammo in the mag at least a couple of times a year before loading up with my range ammo. Been doing this for many years with no issues. If a spring is not moving, it's life expectancy is not being diminished in any way.
Targets Guy
US Veteran
After 4 years the springs in my 1911s are still working fine.
Definitely agree with the consensus that there is no basis for the idea that keeping magazines loaded will have negative effects.
There are no time-dependent terms in the equations for design/analysis of springs (static loading/stress).
Loading and unloading will add a *tiny* bit to the fatigue stress but if the spring is designed properly it should withstand a million or so cycles of alternating stress. A person would likely wear their fingers out before the spring breaks.
(an exception is if the spring has a manufacturing defect that causes a stress concentration, but that's a special case)
There are no time-dependent terms in the equations for design/analysis of springs (static loading/stress).
Loading and unloading will add a *tiny* bit to the fatigue stress but if the spring is designed properly it should withstand a million or so cycles of alternating stress. A person would likely wear their fingers out before the spring breaks.
(an exception is if the spring has a manufacturing defect that causes a stress concentration, but that's a special case)
Walt Sherrill
Member
Some of your guys don't understand how springs wear. This has been addressed elsewhere on this forum in related discussions.
Coil springs wear slowly with use, but the wear very slowly when they're not compressed (or stretched) to near their design limits.
Not all magazine (or recoil) springs are fully compressed when the mag is fully loaded or the slide is locked back. But, if the springs ARE compressed near or beyond that limit, as can happen with some hi-cap magazines, the springs can degrade when they're left loaded. And it can happen relatively quickly.
Some gun designs don't push their coil springs to their design (elastic) limits. But many of the very small gun designs do, as do some of very high-capacity magazines.
Need some examples of this sort of wear when a spring is pushed to the spring's elastic limit?
On another forum, one member talked about how the NCOIC of his National Guard unit's Armory left all of the unit's M9s with slides locked back over the winter; nearly all of them had to have their recoil springs replaced in the Spring before anyone could take them to the range.
I'll be very surprised if you don't see a significant change in that recoil spring's behavior. (It might be good to buy a spare recoil spring for the gun you test...)
Properly designed and properly used magazine or recoil springs can outlast the gun. But with some designs (like the very small 9mm and .45 semi-autos) use much smaller springs in smaller spaces to make the guns do what they're designed to do. Those springs just don't last as long -- even though they aren't cycling as much as the springs in full-size guns. With some gun designs, the recoil or magazine springs are "renewable resources."
The same is true of some but not all high-cap mags. If the coil springs in the magazines are near their design limits when fully loaded, if you're storing them loaded for long periods, downloading them a round or two will assure they work right when you next need again. (I leave mine unloaded.)
Recoil springs and magazine springs CAN DEGRADE if left fully compressed for long periods, but only if, when fully compressed, the springs are near their design limits. But MORE than cycling can degrade springs.
Do the S&W mags being discussed push their springs to their elastic limits? I don't know. But assuming that they don't may not be correct.
Coil springs wear slowly with use, but the wear very slowly when they're not compressed (or stretched) to near their design limits.
Not all magazine (or recoil) springs are fully compressed when the mag is fully loaded or the slide is locked back. But, if the springs ARE compressed near or beyond that limit, as can happen with some hi-cap magazines, the springs can degrade when they're left loaded. And it can happen relatively quickly.
Wolff Springs addresses this on their FAQ page. They call that limit the elastic limit of the spring. Wolff recommends downloading a round or two for long-term storage as a general rule, but it may not be necessary for all high capacity magazines. Wolff doesn't recommend doing that when carrying the weapon, however.
When the spring is compressed to its elastic limit the metal will begin to degrade, through many micro-fractures in the spring material. As already stated, not all coil springs are pushed to their elastic limits during normal cycling.
Pushing (compressing or stretching) a coil spring to its limit is what causes wear. Releasing the spring reduces the likelihood of wear or damage.
When pushing or stretching a spring to that limit the metal will being to undergo micro-fractures (a type of metal fatigue). That happens at or near the spring's design limits. Easing up on that stressing condition (as happens when a shot is fired in a magazine) reduces the likelihood of damage. In other words, loading the magazine can be harder on the spring than cycling the spring.
When pushing or stretching a spring to that limit the metal will being to undergo micro-fractures (a type of metal fatigue). That happens at or near the spring's design limits. Easing up on that stressing condition (as happens when a shot is fired in a magazine) reduces the likelihood of damage. In other words, loading the magazine can be harder on the spring than cycling the spring.
Some gun designs don't push their coil springs to their design (elastic) limits. But many of the very small gun designs do, as do some of very high-capacity magazines.
Need some examples of this sort of wear when a spring is pushed to the spring's elastic limit?
Folks who shoot suppressed or silenced weapons often find that after a suppressor or silencer is installed on a handgun, the guns will no longer properly cycle the slide.
How do they make the gun cycle properly using the same ammo? By leaving the slide locked back for several days or a week. That weakens the recoil spring just enough that the gun will cycle but still have enough stored force to chamber the next round.)
How do they make the gun cycle properly using the same ammo? By leaving the slide locked back for several days or a week. That weakens the recoil spring just enough that the gun will cycle but still have enough stored force to chamber the next round.)
On another forum, one member talked about how the NCOIC of his National Guard unit's Armory left all of the unit's M9s with slides locked back over the winter; nearly all of them had to have their recoil springs replaced in the Spring before anyone could take them to the range.
If you doubt this, there's an easy test: lock back the slide on one of your smallest semi-autos and leave it like that until Spring; then take it to the range and then tell us whether it cycles properly, and if it does, tell us how far it ejects spent cases.
I'll be very surprised if you don't see a significant change in that recoil spring's behavior. (It might be good to buy a spare recoil spring for the gun you test...)
Properly designed and properly used magazine or recoil springs can outlast the gun. But with some designs (like the very small 9mm and .45 semi-autos) use much smaller springs in smaller spaces to make the guns do what they're designed to do. Those springs just don't last as long -- even though they aren't cycling as much as the springs in full-size guns. With some gun designs, the recoil or magazine springs are "renewable resources."
The Rohrbaugh R9, which was probably the smallest quality 9mm semi-auto available, had/has a very short barrel, a very short frame, and uses a very small recoil spring. That recoil spring was originally intended to last 300 cycles, but Rohrbaugh later changed that to a recommended 250 cycles. (The springs weren't that expensive, and Rohrbaugh was concerned that a carry weapon that he designed and sold be reliable when used, so he probably erred on the side of good functionality.)
The same is true of some but not all high-cap mags. If the coil springs in the magazines are near their design limits when fully loaded, if you're storing them loaded for long periods, downloading them a round or two will assure they work right when you next need again. (I leave mine unloaded.)
Recoil springs and magazine springs CAN DEGRADE if left fully compressed for long periods, but only if, when fully compressed, the springs are near their design limits. But MORE than cycling can degrade springs.
Do the S&W mags being discussed push their springs to their elastic limits? I don't know. But assuming that they don't may not be correct.
joe44va
Member
Back in the 1990s I bought a bandoleer of M1 Carbine mags. 5 were still loaded with LC 43 rounds. All fed and fired without malfunction. Who knows how long they were in there. The guy I bought them from said they were from a Korean war vet.
Bozz10mm
US Veteran
I keep my handguns loaded, but I have several mags for each handgun. I rotate them out with a different mag every time I go to the range, usually once a month. If they aren't in the pistols, I don't keep them loaded.
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I have never had a pistol magazine weaken from being fully loaded.
But after a few years of being fully loaded the magazine spring in my Remington 870 shotgun couldn't push the last round completely out of the magazine. I only shoot the 870 a couple of times a year and do not shoot a lot of rounds through it when I do so it didn't get weak from use.
I would leave the magazines in your pistols loaded. Maybe to one less than capacity if you are worried about it. Worst case S&W will sell you new magazine springs for $3.28 plus shipping (M&P9/40 Magazine Spring (10,12,15,&17 Round)).
A weak magazine spring typically results in a failure when the last round or two is fired and the spring is weakest.
But after a few years of being fully loaded the magazine spring in my Remington 870 shotgun couldn't push the last round completely out of the magazine. I only shoot the 870 a couple of times a year and do not shoot a lot of rounds through it when I do so it didn't get weak from use.
I would leave the magazines in your pistols loaded. Maybe to one less than capacity if you are worried about it. Worst case S&W will sell you new magazine springs for $3.28 plus shipping (M&P9/40 Magazine Spring (10,12,15,&17 Round)).
A weak magazine spring typically results in a failure when the last round or two is fired and the spring is weakest.
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I can only offer this observation. The magazines for our M-16's in the Air Force Security Police Armory were kept loaded 24/7 for many years at a time. The 30 round magazines were emptied only for random inspection of the rounds and were promptly reloaded. The only magazine failures that I observed were of the floor plates bowing and eventually popping out on occasion. Certainly no lack of spring tension there. In one armory this was for over 300 rifles with four magazines each.
kthom
Member
If one is concerned about exceeding the compression limits of the magazine spring as mentioned by Walt, then just load your mags with one round less than completely full during storage. The mag is still ready to go if needed but the spring is not fully compressed so should not be compressed beyond the limit. I normally load my mags completely and then load the top round into the chamber, leaving the mag spring not fully compressed. Sometimes I will top of the mag of my EDC after loading so as to have a full load. I think it is a good idea to count rounds carefully while loading mags so as not to try to press in another round on top of a mag that's fully loaded. But again, I have no problem leaving magazines loaded for long periods of time. I have had no issues with mag springs except for a few mags that had been loaded, fired and reloaded for probably thousands of times. My mags are marked so I can keep up with the ones that are used most often.
Walt Sherrill
Member
All gunmagazine designs -- and the coil springs that make them work -- are not the same. Some will last for years, if left fully loaded, others won't.joe44va said:
There are many examples of 7-round 1911 magazines that have been left FULLY LOADED for 50+ years (WWII bringbacks, for example) and they continue to function properly. But that's because the 7-round magazine spring, when the mag is fully loaded, is nowhere near the spring's elastic limit. Try that with a very high capacity 9mm magazine and see what happens...
The springs won't all fail if left fully loaded, but nearly all of them will show spring power loss. Many of them will continue to function well for years; a few just won't work.
If cycling coil springs is what wears them out, I wonder why many automobile engine valve springs never fail -- as some of them will be compressed many millions of times over a period of a few years. And engines that run for 10-20 years without failures probably have springs that have cycled billions of times.
Know why? Because the engineers who designed the engine designed and specified the valve springs did so in a way that the spring, when working, were NOT pushed to or beyond their elastic limits!
With many modern guns, the only way to make a gun smaller or to make a magazine hold more rounds (while still fitting in the grip) is to make something else smaller. In some cases it's the recoil spring (to fit in a smaller space in the frame or a shorter barrel), or with high-cap mags, to make the magazine spring a bit smaller, using a lest robust spring (smaller diameter metal) that has a higher spring weight.) It's stronger, but won't last as long.
There are no free lunches, and making springs smaller but requiring them to do the same work as larger, more robust springs, the spring won't -- can't -- last as long.
Some folks willingly give up a bit of spring life for that smaller gun or higher capacity magazine, so the gun designers are doing exactly what was wanted.
It was much less common, when I first started shooting a little in the late 60's, and got much more active in the late 90's, to even find replacement springs or to see people try to do that. When mags quit working, people tossed them and bought new ones.
You can still read a lot of responses on gun boards where, when a mag doesn't function properly, the gun owner just tosses the mag and buys a new one; they didn't know that a new $4-$5 spring might fix the problem.
ScaryWoody
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I do industrial trade shows and spoke to a spring supplier. They made all sorts of springs including firearm springs. I asked about the wear and compression life. They told me that the spring is un-effected by compression over extended periods. they have greatly improved spring life versus 30 plus years ago. Metallurgy and heat treat technology has vastly improved spring performance.
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Real Old Navy
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Bed springs only wear out faster if they're moving up and down more...think about that one for awhile.
Walt Sherrill
Member
ScaryWoody said:
A number of engineers on other forums (several in the aerospace industry) and one who is a Metallurgist, disagrees with your supplier (who may be a sales rep and not someone involved in spring design.) If you see that supplier again, ask him about "elastic limits" and if any of the springs they produce are ever pushed to their elastic limits. (Elsewhere this point is called a spring's "yield point" or "design limit.")
Then read through the following link:
https://www.thebalance.com/metal-str...lained-2340022
The following is taken from this link. The second sentence in the first paragraph is a key point. When applied to coil springs, it says, in effect, that if you don't compress the spring to its yield point (also known as it "elastic limit,") the spring may suffer some wear, but may continue to function well for a long, long time. But if or when you hit the yield point, things can go south, and go there quickly. This is seen in a long-term test referenced later (below).
Metal Fatigue Resulting from Metal Strain
When ductile metals are stressed, they deform. If the stress is removed before the metal reaches its yield point, the metal returns to its former shape. While the metal appears to have returned to its original state, however, tiny faults have appeared at the molecular level.
Each time the metal deforms and then returns to its original shape, more molecular faults occur. After many deformations, there are so many molecular faults that the metal cracks. When this occurs, it is described as "metal fatigue." Metal fatigue is irreversible.
Metal fatigue is particularly problematic in situations where metal is stressed over and over again. For example, it was a major cause of aircraft failure before it was fully understood. To avoid metal fatigue, it is important to examine samples of metal under stress using a microscope regularly.
When ductile metals are stressed, they deform. If the stress is removed before the metal reaches its yield point, the metal returns to its former shape. While the metal appears to have returned to its original state, however, tiny faults have appeared at the molecular level.
Each time the metal deforms and then returns to its original shape, more molecular faults occur. After many deformations, there are so many molecular faults that the metal cracks. When this occurs, it is described as "metal fatigue." Metal fatigue is irreversible.
Metal fatigue is particularly problematic in situations where metal is stressed over and over again. For example, it was a major cause of aircraft failure before it was fully understood. To avoid metal fatigue, it is important to examine samples of metal under stress using a microscope regularly.
The metal used in gun springs are typically high-yield stainless or carbon steels that are alloys that include other materials that let the metal have a high yield level (i.e., they can bend without damage). (Stainless steel is used for its corrosion resistance.)
Then read through the following topics on Wikipedia. They address definitions and concepts central to this discussion. I may be able to find others, but keeping these sort of links live (i.e., working) is a challenge, as some of these sites change frequently. These all worked when I posted them:
Elasticity (physics) - Wikipedia
Plasticity (physics) - Wikipedia
Viscoelasticity - Wikipedia
Creep (deformation) - Wikipedia
Finally -- if cross links are allowed (I think they are) -- look at this link to a similar discussion on The Firing Line another forum that other members here visit. It will show some tests done by a staffer there over an extended period. The staffer there, JohnKSa who did the work. He's reasonably familiar with a lot of different firearms, is an engineer, and has had a long-term interest in spring-powered air guns. He also doesn't rely on theory, alone, or "accepted truths" that may or may not be true.
https://thefiringline.com/forums/showthread.php?t=557865&highlight=magazine+spring+life
Finally, remember the point I made several times earlier in this discussion: long-term compression is ONLY a problem if the spring, when compressed, is compressed to a point that nears or exceeds the spring's elastic limit (i.e., its design/ yield limit.)
Not all springs in a magazine will come close to that limit when the mag is fully loaded, but some guns may find it necessary to push mag or recoil springs to that point -- because its the only way to get the capacity of functionality required.
That springs are only worn by being worked is an article of faith for many shooters. And, in their defense, until hi-cap mags and very small guns became popular, there was little or no reason to question that belief. It's still generally true, as most springs in many gun designs are never pushed enough to cause wear-related function problems. But some gun designs go the other way, and those springs will degrade far more quickly than is generally the case.
The graphs showing spring wear in long-term spring compressing in the FIRING LINE link above shows some of this -- some of the springs tested show significant loss of power after being compressed for long periods, but all of those springs still continued to function as they should. But wear occured when there was NO CYCLING!!
If you or others involved in this discussion can find contradictory technical information feel PLEASE share it with us.
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kdub
Member
This is all great info. Thanks. So given that this is an M&P forum, how do M&P mag springs rate regarding this info? Are the 17-round mags pushed to the limit when fully loaded? The two different sizes of Shield mags? The 15-round Compact 2.0 mags? Etc., you get the idea.
Thanks in advance to the answers.
Thanks in advance to the answers.
Walt Sherrill
Member
I haven't had any M&Ps long enough to answer your questions -- and I don't keep my mags loaded when they're not in use. Others will have to give you some answers.
I continue to be amazed by Glock magazines, which I've used a lot over the years, and never had a mag spring fail. I do know, however, that with new Glock mag, you may need a bumper jack to fully load the mag; Glock uses stout springs.
I have replaced other hi-cap mag springs over the years, in other guns, but never a lot, and sometimes they were in guns I got in trade.
I remember that I once had to replace six mag springs for a Kahr P9, all at the same time. I bought that gun used from a Maryland police officer, played with it for a while and never had a hint of problems; I suspect the prior owner kept his carry mag and spare mags fully loaded. While those are NOT hi-cap mags, the springs are deeply compressed when the 8-round mags are loaded.
I continue to be amazed by Glock magazines, which I've used a lot over the years, and never had a mag spring fail. I do know, however, that with new Glock mag, you may need a bumper jack to fully load the mag; Glock uses stout springs.
I have replaced other hi-cap mag springs over the years, in other guns, but never a lot, and sometimes they were in guns I got in trade.
I remember that I once had to replace six mag springs for a Kahr P9, all at the same time. I bought that gun used from a Maryland police officer, played with it for a while and never had a hint of problems; I suspect the prior owner kept his carry mag and spare mags fully loaded. While those are NOT hi-cap mags, the springs are deeply compressed when the 8-round mags are loaded.
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Flyingfool
Member
I usually have all my shield mags to capacity, as well as my 2.0 9c.
I think from now on, I will download all the mags by one round. Then if I go and carry, I will pop in the one round on the carry mag as well as rhe extra mag(s) I carry. Then download again when I return home.
I have been considering buying a spare RSA for each gun nust to have on hand should one finally give up the ghost! Then order another and always keep a spare on hand. Possibly might be a consideration for one mag spring for each model as well. They are not that expensive to have as a back up.
I think from now on, I will download all the mags by one round. Then if I go and carry, I will pop in the one round on the carry mag as well as rhe extra mag(s) I carry. Then download again when I return home.
I have been considering buying a spare RSA for each gun nust to have on hand should one finally give up the ghost! Then order another and always keep a spare on hand. Possibly might be a consideration for one mag spring for each model as well. They are not that expensive to have as a back up.
This is a controversial subject.
I can tell you at my old PD Glock mag springs would take a set from sitting loaded.
Our armorer would compare against a new spring during annual inspections, and replace those springs he found had shortened to a point he didn't feel comfortable with.
I can assure you the majority of the department mags issued did not see regular cycling, most just sat between qualifications.
This happened with my own issued Glock 17 & mags.
During the last inspection before I retired, the armorer showed me how much the springs had shortened.
The only malfunction I ever had in that Glock was a mag-induced feeding failure, when a round jammed too far down for the slide to pick up.
Whether or not that was spring related, I don't know.
I routinely carried every mag downloaded by one after that, just to relieve SOME pressure on the springs.
And the spring shortening still happened.
Denis
I can tell you at my old PD Glock mag springs would take a set from sitting loaded.
Our armorer would compare against a new spring during annual inspections, and replace those springs he found had shortened to a point he didn't feel comfortable with.
I can assure you the majority of the department mags issued did not see regular cycling, most just sat between qualifications.
This happened with my own issued Glock 17 & mags.
During the last inspection before I retired, the armorer showed me how much the springs had shortened.
The only malfunction I ever had in that Glock was a mag-induced feeding failure, when a round jammed too far down for the slide to pick up.
Whether or not that was spring related, I don't know.
I routinely carried every mag downloaded by one after that, just to relieve SOME pressure on the springs.
And the spring shortening still happened.
Denis
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