Mag spring integrity - loaded vs. unloaded

[Walt Sherrill]

Keep in mind this thread is about magazine springs. And I'm jumping to the conclusion that quality magazine makers select springs that aren't stressed past their elastic limit when the magazine is fully charged and pressed against the bottom of a slide.

For full-size guns, that argument makes sense. But, for some of the compacts and sub-compacts, both recoil springs and mag springs, I don't think springs can do what they need to do in those smaller guns and last for a very long time.

A number of the different gun makers who build the small 1911s recommend changing the recoil springs far more frequently than they do with full-size guns. (One of them recommends changing the recoil spring about every 500 rounds for one of its small guns, but suggest 3000-5000 rounds for their full-size guns.)

As several folks here have mentioned, gun designers seem to be pushing springs farther today than they ever pushed them in the past -- to make the mags hold more rounds and to make guns with shorter barrels cycle properly. What if the only way you can get a gun to function properly and still meet its design constraints of small size, is to design it so that you assume the springs are overworked, and won't last as long. I think that IS HAPPENING today with many of the new guns that aren't full size.

A sub-compact .45 or .40 must still handle the same round/force as a full-size gun, and do it with a spring that takes up far less space. You can argue that a properly-designed spring in these smaller guns will still work just as long, but that seems to be an article of faith, as none of them seem to be doing it.

The point that others have made, however, is that some springs are just crap from the day they were made, due to cheaper materials and poor design. That's why many folks stick with factory mags or Mec-Gar mags. (And we know that Mec-Gar makes many of the factory mags for many gun makers.)

.

[Sport45]

^^ I emphatically agree. ^^

[danez71]

So how is it the valve springs in a '83 pickup truck with 150,000 miles can still meet tolerance for height and compression? That's after being compressed for 25 years and cycling to near-stack some 135 million times? (I put them back in.)

Easy. Toyota typicaly over builds their products and because of that has earned the reputation of longevity. Another example though is that the 22RE 4 cyl motor in their trucks is well regarded. In the mid 80's they pumped up the power numbers (new cam etc) and put that motor in thier Supra GT-S. That sports car never earned the same reputation of longevity. They pushed the limits of that motor to the point of sacrificing durability. But back to mag springs like you mention below.

A paper clip is a good example. You can bend it back and forth until it breaks. That's fatigue failure. Have you ever seen a paper clip break from normal use?

Keep in mind this thread is about magazine springs. And I'm jumping to the conclusion that quality magazine makers select springs that aren't stressed past their elastic limit when the magazine is fully charged and pressed against the bottom of a slide.

A paper clip isnt any type of spring steel but lets talk about that for a moment. No, I havent seen a paperclip 'break' from use, but I have seen them wear out to the point they cant hold their shape well enough to hold paper even after bending it the other way.

Flexing/compression causes stress. Stress causes fatigue. No two ways about it. But now you've skipped that and are now talking about operation past their 'elastic limit'.

Their elastic limit is NOT a finite amount. The more you stress it... the faster it wears.

I'm making this example up as their are too many variables. All things being equal....
If a spring is compressed 10% it may last 2 mil cycles as designed. Compress the same spring 20% and it may only last 1.5 mil cycles. Compress it 50% and it could down to 500k cycles. Compress it 80% and it may only last 10k cycles.

The valve spring in motors are massive in thickness as compared to a mag spring. They also dont compress as much either. The valve spring is probably around 3 inches long and the lobe on the cam is maybe .3"-.4"...? Lets call it .5" on a 3" spring is only about 16.667 % compression. (not to mention valve springs are sometimes a 2 spring set - inner and outer)

The mag spring is being compressed WAAAAAY more than 16%. Its also probably about 1/10 the diameter of a valve spring. Thats how get such different results in durability between those two comparisons.

Toyota doesnt want to warranty a motor because a valve spring let go. Gun mfg's send you a new spring and dont have to worry about replacing a $5k-$10k gun (or motor to toyota).


Single stack mags are actually more susceptible IMO. To make things easier I'll use easy #'s. Eight 9mms in single stack would be about 3" of spring travel in a roughly 4.5" mag. They stack fairly straight. Twelve 9mm double stacked (not truly double stacked but...) would cause less spring travel in the same length mag. The Eight 9mm single stacked would actually push the mag spring deeper into its elastic range and thus shortening its life.

For brevity, I left out the however part. But how can you "agree in loose terms" with this and believe the same thing said with different words is wrong on so many levels? All in the same post?

Fair question. 1st, you said cycling the spring doesnt cause wear. That isnt what the other guy said that I some what agreed with and thats a big difference.

2nd. He's right from the sense that a "properly designed and mfg spring" for the most part will last a loooong time.

But whose definition of properly designed spring are we using? Ours? Or the practical limitations placed on engineers that include cost?

On full size guns there is more room to work with and things can be built more robust. Sure, they could change the material but at what cost? Will the extra cost be justified by the extra durability?

Look at all of the sub compacts coming out and all of the spring issues (usually the slide) that have popped up. In a BHP they could put a 3+" spring in there. The Roughbaugh shoots the same 9mm with the same length but because of its size, the spring has to compress a much greater % than the full size. Its no coincidence that Roughbaugh (and other subcompacts)recommends frequent spring changes.

I hope that better explains what and why I said what I did.

[Bill DeShivs]

Can someone tell me what happens to a carbon steel spring when it wears out? What are the symptoms?

[Sport45]

On second thought, never mind...

[JohnKSa]

And I'm jumping to the conclusion that quality magazine makers select springs that aren't stressed past their elastic limit when the magazine is fully charged and pressed against the bottom of a slide.

Sorta...

For example, Beretta recommends (at least in my 92G manual) that you not top off the magazine after chambering a round since a fully loaded magazine inserted in the pistol has about the same stress on the spring as a spare magazine stored outside the gun. They imply but don't actually come straight out and say that stressing the spring beyond what would normally be encountered in a full spare magazine (not inserted in the gun) has a negative effect.

(In case you're wondering what the difference is, the slide adds a bit of downward force on the top round when the magazine's inserted in the pistol.) They then go ahead and tell you the approved method for fully loading the pistol (round in the chamber & topped off magazine), so they're obviously not saying that it ruins the magazine but they make it clear that it's better for the spring to not top off the mag.

So how is it the valve springs in a '83 pickup truck with 150,000 miles can still meet tolerance for height and compression? That's after being compressed for 25 years and cycling to near-stack some 135 million times? (I put them back in.)

The engine has a considerable amount of power that it can use to compress the springs. Magazine springs could be made to never wear out under any circumstances but they would be impossible to load and would be strong enough that one would have to worry about them deforming the rounds.

Even if we assume ideal materials and proper manufacturing processes, magazine springs are a delicate design balance of:

1. Spring life.
2. Capacity.
3. Ease of loading.

If you overemphasize any one of those parameters the other two will suffer at least slightly.

[Walt Sherrill]

Can someone tell me what happens to a carbon steel spring when it wears out? What are the symptoms?

The symptoms I've seen most often begin with failures to feed.

Sometimes I'll see the tips of the top rounds nose-diving while in the mag. (And no, the follower isn't installed incorrectly.) And nose-diving as they hit the feed ramp, when hand-cycled.

Sometimes I'll notice as I'm loading the mags that there will be much less resistance than in the past. In a few cases, the rounds will slip and slide inside the mag tube, and seem to stick, while loading or while being unloaded or used; I've seen the topmost rounds simply fall out, if you hold the map upside down, with some jammed in the tube. I've noticed this most often with hi-cap mags, but as one person noted, it can happen with the single-stack mags found in some of the compact mags.

Failures to feed were the big problems with my Kahr P9; new mag springs made it perform like a new gun.

I've had any number of friends with 1911s who swear by 7-round factory mags, and swear at the 8-round factory mags, regardless of maker. I tried a few 10-round 1911 mags, but found them awkward (size/appearance), so don't know how they stand up.

Another respondent noted that double-stack mag springs don't have to be compressed as much as single-stack mags, because of their staggered load. the amount of compression is apparently a critical factor.

I've never had any of these problems with a 10-round mag in a full-size 9mm handgun. I've noticed that generally, the same spring is used in the hi-cap mags as are used in the 10-round version. (That is certainly true of the S&W 59XX series, the CZ mags, and Witness and Beretta mags.) In these cases, the same spring is doing 50%+ more work in the hi-cap than in the 10-round mag-- so the problem isn't material or design, but how the material is used.

[jmortimer]

If I'm going to leave a magazine loaded for extended periods I do not load it to max but one or two rounds less than max.

[Tactical Jackalope]

Wow! I'm really impressed. When you know what to look for (and how to decide whether you've found the right stuff), you can find marvelous stuff on the internet.

Thanks.

The Moderators ought to make this message chain a STICKY, somewhere.

+1 From my end on this too.

Also, I seriously did laugh out loud..Although confused that I couldn't see what "gunnotes" was saying until the "Has left the building" statement. Hilarious about time...




Back to the topic..I have all my 1911 mags to capacity, Glock mags, XD, Browning high-power, S&W .22, my old mans phoneix arms and his 9mm....



Basically asking if I'm damaging them? I was always under the impression that magazine springs get worn from use and only use..But makes more sense I guess if it's always forced down by 7-17 bullets on top of it making it to capacity. Right?

[Brian48]

Since we're talking about mag springs, has anyone used Wolff extra power springs in their 1911 mags? If so, what are your experiences?

My standard 7rd .45acp mags and 8rd 10mm mags are getting close to 20 years old and have seen hard use. Just ordered a bunch of these to refresh them, but now I'm wonder if I should have stayed with the standard weight springs.

[Bill DeShivs]

Walt-
You mean the springs get weaker?
My experience with spring wire is this:
Springs work-harden, get brittle, and break-but don't get weaker.
I'm learning that some spring makers use substandard material. If carbon steel spring wire is not used, anything is possible.

[Will Beararms]

#1

I was taught from an early age to fill a mag to one less than full capacity while in storage. So far, it has never let me down.

#2

Mags should not fail early on in a Kahr top of the line pistol for what you pay for one IMHO.

[Walt Sherrill]

Walt-
You mean the springs get weaker?
My experience with spring wire is this:
Springs work-harden, get brittle, and break-but don't get weaker.
I'm learning that some spring makers use substandard material. If carbon steel spring wire is not used, anything is possible.

Yes, I mean that springs (in some applications and situations) can get weaker. But with some springs/mags, the amount of weakness may be trivial. It depends on the design of the mags, the steel used, etc.

If you read the various technical articles cited in some of the discussion, that is exactly what happens -- even with well-designed mags using the best materials.

I suspect that were we to continue to try to use the WEAK springs, they'd break two -- as I wouldn't be surprised if some of the steel's internal structure is breaking as it degrades, causing the weakiness. A little breakage may equal weak; a lot of breakage may equal snap. When mag springs start to go bad, most of us don't stretch them or try to keep using them, so I don't know what would happen next. Mine wouldn't work, so I replaced them. They didn't "snap" as your experience indicates.

This degradation may not be a common problem and it may not happen (i.e., be severe enough to notice) with all mags; but it would appear that there is degradation, over time, even if the mags are NOT cycled heavily, but are just kept under some load. After a point, the more compressed, the more likely degradation is to occur. It may be trivial or more meaningful, depending on the mag design, how the springs are built, and the amount of compression. One of the articles indicated that a greater compression load accelerated the wear; if it wasn't pushing the limits, the amount of wear/functional loss was not great...

I was surprised to read that single-stack mags (perhaps like those in my Kahr P9) might degrade more quickly than some of the double stack.mags It depends on the gauge/thickness of the steel, the type of steel used, the amount of compression required, etc. Did you read any of that? It was interesting. I couldn't understand why I had 8 mags go bad almost all at the same time. Kahr single-stack 7 and 8 round mags for the P9. I didn't keep them loaded, but they were used, and I did shoot them a good bit right before I sold the gun the first time.

But, as I've said several time, I've got mags that are still function properly 10-15 years after purchase; some of these have been left fully loaded for extended periods.

And as someone above noted, a person is free to leave their mags fully loaded, regardless of their type, and just check them periodically, by using them. Others here say they will do as Wolff Springs suggests, and download them a round or two for extended storage periods.

Later note: I've had springs on car doors and screen doors get weak, and I've had coil and leaf springs in cars lose their ability to return to their normal positions. (That sort of car-spring failure is not common -- I've only personally seen that once or twice in MY CARS despite almost 50 years of car ownership. But that included some pretty rough cars, back when I was struggling to make ends meet. I haven't experienced a car spring failing by breaking, yet -- but I'm wouldn't doubt that it could happen.)

[JohnKSa]

Springs work-harden, get brittle, and break-but don't get weaker.

I've repeatedly posted the link to a spring piston airgun test showing that springs weaken when left overcompressed for long periods of time.

The results are repeatable and mirror the results of a similar test published in Tom Gaylord's excellent book on the Beeman R1 airgun.

Even with the highest quality springs from custom makers the effect is still noted although the best quality springs showed the least weakening.

http://www.network54.com/Forum/79537...re%27s+a+test-

I started out with airguns many years ago before I began shooting firearms. When I began shooting and learning about firearms I was quite surprised to find out that what was common knowledge in the spring-piston airgun world (that springs will weaken if they are forced to absolute maximum compression and left that way for long periods) was considered to be myth by many in the firearm world.

[Bill DeShivs]

I repair automatic knives-lots of them, from 150 years old to brand new.
These use leaf springs that are put under much more stress than any magazine spring. I have dealt with literally thousands of knives.
I have seen exactly zero with weakened springs. They either work, or break.
When I make a new spring from 1095 steel, the spring takes a small initial "set" the first time the spring is compressed. Once set, the springs remain stable.
My experience with gun springs is not as extensive, but still more than most people's. I have never replaced a spring, save 2 guns that were in fires.
I'm not saying "weakening" springs don't happen, as there is far too much evidence to the contrary. It just doesn't make sense to me. I still say that:
Properly made, properly designed springs don't just get weaker.
Even the subcompact pistols that abuse springs shouldn't weaken.
Again, my experience is with carbon steel springs only-but you have to admit I have much more experience than most people. No one has really been able to explain the phenomenae to me.

[Walt Sherrill]

These use leaf springs that are put under much more stress than any magazine spring. I have dealt with literally thousands of knives.

I don't doubt your experience.

What informs your claim that leaf springs "are put under much more stress than any magazine spring?"

I just wonder whether leaf springs are simply a different animal than the coil springs used in magazines and recoil springs, and we're really talking about apples and oranges...

[Sport45]

I just wonder whether leaf springs are simply a different animal than the coil springs used in magazines and recoil springs, and we're really talking about apples and oranges...

With a magazine spring you're really talking about apples and oranges at the same time.

The flat part of the spring acts like a leaf spring in that it is subjected to bending stress. The rounded part acts like a coil spring since it is subjected to torsional stress. I haven't studied magazine springs in detail, but I imagine most of the work is done by the end coils in torsion.

Coil springs, like all recoil springs I've seen, are torsional springs. That is the cross-section of the wire is twisted as the spring is compressed and relaxed.

[danez71]

I just wonder whether leaf springs are simply a different animal than the coil springs used in magazines and recoil springs, and we're really talking about apples and oranges...

Yep....

Coil springs, like all recoil springs I've seen, are torsional springs. That is the cross-section of the wire is twisted as the spring is compressed and relaxed.

Pretty well said. Also the rectangular shape of a mag spring results in even more torsional stress than a true circular coil.


I only know of 1 truck (Dodge 1/2T, not any of the sport trucks) in current production that use coils in the rear. The design of the leaf spring spreads the loads out over a much greater percentage of matial as compared to a coil.. especially a rectangular coil.

[Bob Knizner]

JohnKSa:

I've repeatedly posted the link to a spring piston airgun test showing that springs weaken when left overcompressed for long periods of time.

This is impossible to refute, but what is the definition of "overcompressed" in this context? How does the degree of compression seen in this airgun spring compare to that expected in a full size pistol mag spring?

There is a lot of good information posted above that opens up a great discussion. What is missing in many of these discussions, especially when the topic is the application of esoteric and poorly understood physical properties of materials, is an understanding of the degree to which these properties effect the things we are talking about in the real world.

How many times will a mag spring be cycled? Most less than 1K times, I bet. How much degradation of rate will cause a malfunction given the safety (fudge) factor in the design spec? How many years of compressed storage will this degradation take to occur?

We are talking about springs of many designs, with different metallurgy, heat treatment, cross sectional shape, surface treatment and finish, coil shape and radius, end design, degree of compression from a free state, and on and on.

How can we make a blanket, all encompassing statement as to whether or not, for all springs in all magazines, that loaded storage will or will not decrease the spring rate in our lifetimes?

Also, the whole topic of a non-defective mag spring being cycled enough times, in the real world, to degrade sufficiently to compromise its function is an example of the distinctions between what is "possible" vs. what is "probable".

When you lump poorly made springs or those that are compressed beyond or very close to their elastic limit into the discussion, all bets are off and we should be talking about proper mag design and spring QA, not the properties of steel springs.

Bob

[Walt Sherrill]

When you lump poorly made springs or those that are compressed beyond or very close to their elastic limit into the discussion, all bets are off and we should be talking about proper mag design and spring QA, not the properties of steel springs.

I really don't think most of the participants here have conflated good and bad materials, and good or bad designs. I, for one, citing other sources, have noted that some springs seem to live forever. Spring makers, like Wolff, talk about pushing springs to or beyond their design limits.

It seems increasingly likely that gun designers are, on purpose, pushing gun springs to new limits -- using the springs as a renewable resource. How else can you get small guns to perform like large guns, and hold almost the same number of rounds; the space limitations are just a difficult hurdle to overcome.

I've had mag springs fail -- and they were arguably good quality springs in mags made by reputable manufacturers like Mec-Gar. (I've had long-lived springs, too.) Yet I continue to hear, on forums like this, that springs simply don't fail.

Not so. This whole discussion was an attempt to explore the subject, and coupled to the recent technical citations, and an earlier effort, cited in one of my responses, a number of folks have provided a lot of good information.

Perhaps you can bring additional information or experience to the discussion, to help us better understand the topic... We already understand the weaknesses of the pro and con sides of this debate; can you offer something new?

[danez71]

We are talking about springs of many designs, with different metallurgy, heat treatment, cross sectional shape, surface treatment and finish, coil shape and radius, end design, degree of compression from a free state, and on and on.

Totally agree. We are talking about something that people have careers for. We will never know the exact answer for every spring... in every application... unless we start funding tests.

How can we make a blanket, all encompassing statement as to whether or not, for all springs in all magazines, that loaded storage will or will not decrease the spring rate in our lifetimes?

This is easy. Ive already posted the evidence... at least once; All materials exhibit viscoelastic deformation under light strain at room temp.


The real question is... How long does it take, and how much has to occur, for viscoelastic deformation to render the gun unreliable?

Answer: With out testing, we wont know for sure.

While Ive mostly been championing that it does occur with every spring, Ive also said that it may not make a difference for a looong time in some applications and much quicker in other applications. (paraphrasing)


Ive mostly been championing that aspect because the amount of times Ive seen the myth stated that loaded mags wont compromise the spring AT ALL. Its funny to me...its a myth stated as fact trying to debunk a myth that isnt a myth at all.


It would be very interesting if someone bought (for ex) two 13 round mags for a bhp or two 7 round mags for a 1911 and buy 2 for a sub compact... maybe a Sig P238 (?), since Sigs are generally consider a top tier mfg, and load up 1 mag of each for a month or two and take measurements before and after. Not super scientific but it would be helpful.

[Bill DeShivs]

Here is something interesting: Before Wolff came on the scene, hardly anyone changed gun springs, and their guns worked just fine.
I'm sure that spring makers are using substandard materials nowadays.

Now, here is an experiment for you- get a straight piece of piano wire and place it vertically in a vise. Bend it a measured amount in one direction and measure the force it takes to move it that amount. A trigger pull gauge will work. As long as you don't bend the wire past the initial bend radius, it will bend and return straight indefinitely. It will never take less force to bend to the same mark. If someone wants to try this, I can supply some small diameter spring wire.

If you bend the spring wire to the point that it does not return to straight, you have bent it past it's elastic limit, and damaged the integrity of the spring.

The only variable that I don't know about is the rate of compression. In magazines it wouldn't matter-but recoil springs are moved very rapidly. This could play in somehow, possibly creating heat that would tend to affect the heat treating of the spring. Machine gun springs seem to hold up, though.

[Walt Sherrill]

Before Wolff came on the scene people typically threw away bad mags. Many folks still do. That statement doesn't tell us much.

Of course, another participant here (in the earlier mag spring discussion) told us we can just stretch mag springs to restore them to full functionality. I've tried that, and never had the success he had. Mine seemed to work briefly, and then died a second time.

But if springs don't really weaken. but just break -- which was your claim a few messages ago -- why was he stretching them in the first place?

As for your test:

Piano wires are designed to be struck and to vibrate, and each wire is intended to function over a relatively narrow performance range. Are you sure that piano wire is similar enough to mag spring material to say it's a good comparison?

In your test, you're bending the wire, but you're not TWISTING it -- and as I understand it, a mag spring will be expected to both bend and twist to function properly.

Is this really a test, or just an exercise?

[danez71]

As long as you don't bend the wire past the initial bend radius, it will bend and return straight indefinitely.

Bill, with all due respect, you should do some reading.

Nothing is indefinite.

The ONLY thing that is constant is change.

If what you say is true... you just invented an endless supply of energy.

Bottle it.. patent it... and sell it. You have just solved the worlds energy needs for ever.

Supporting evidence is in this thread that disputes your claim.

[drail]

+1 danez71.