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Old January 25, 2015, 12:27 AM   #1
JohnKSa
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Magazine springs

I know, it's a "fun" topic.

It's always entertaining because everyone seems to be an expert on the topic and people tend to have strong opinions about it. It remains an entertaining/exciting subject because there's not much empirical data to rely on which means that it's not easily put to rest.

Awhile back I came up with an idea for a homemade spring tester and built it. You can read about it here.

In December 2013, I picked a new magazine from my safe and started a test. In January 2014, I chose a second magazine and added it to the test.

The first magazine has now been loaded 391 days. The second one 374 days. Neither magazine has been used except in this test. The only loading and unloading that either magazine has experienced is the bare minimum required for the testing. In both cases, that amounts to fewer than 15 loading/unloading cycles.

Both magazines are new, unmodified, factory magazines.

At the beginning of the test, both magazines were disassembled and the uncompressed spring lengths were measured and recorded. The spring strengths at a given compression length were also recorded.

Then each magazine was fully loaded (15 rounds in both cases) and stored in the safe.

At intervals, each magazine was unloaded and disassembled. The springs were measured both for uncompressed length and compressed strength at the same compression depths used in the initial measurements.

The graphs show the results.





It's interesting that both springs showed similar behavior in terms of how the uncompressed spring length changed.

It's just as interesting to see that they behaved very differently in terms of the spring strength changes.

The Ruger P95 magazine steadily lost strength through the first 160 days of the test but then seems to have leveled off at about 27% strength loss. It's worth noting that I tested the magazine in a P95 after the last measurement was taken and the spring is still strong enough to lock the slide back with no problem. I don't intend to test either spring by shooting until I'm completely done with the test.

The Glock 20 magazine has lost very little strength overall but the graph seems to have a slight but steady overall downward trend that apparently is continuing.

Obviously both springs lost a measurable amount of strength (significantly different amounts) and uncompressed length (remarkably similar amounts) from being left loaded.

I'm going to keep the test going until I'm reasonably certain that neither spring is changing any more. If there are any significant changes, I'll post updates.

So some springs do seem to weaken significantly from merely being left loaded. Others do not. How do you know which you have? Short of running a very lengthy test, you probably won't know. How can we deal with this constructively?

My advice is to check your self-defense equipment regularly (we should all be doing this anyway. Right?). If you note springs weakening from being left loaded, replace them with high-quality parts--first you want to eliminate the possibility of quality issues. If they weaken again from being left loaded, replace the springs again but now you've determined that even quality springs may weaken in your magazine design if left fully loaded for long periods. You have two options at this point. You can either underload the mags by a round or two (the last little bit of compression is the hardest on the spring) or you can determine how long the springs will last and simply replace them before they weaken enough to cause malfunctions. Mag springs are cheap, even the best ones.

It is worth pointing out that this test shows not all magazine springs weaken significantly from being left loaded. In fact, as nearly as I can determine, it's not particularly common for magazine springs to weaken from being left loaded to the point that they cause malfunctions. But it can happen and we need to be aware of the possibility so it doesn't take us by surprise. It's one thing to find weak magazine springs at the range or during a routine check. It's another thing entirely to discover the problem during a self-defense encounter.
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Old January 25, 2015, 01:15 AM   #2
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Weakening from being loaded could be from several factors.
Clearly, spring quality is one of them. Also, compression. The design of the magazine body and follower, and the spring itself will determine several things. If the coils are over compressed is one, and whether the compression as the magazine is loaded is straight or not is another. A spring that has more side play can compress crooked, and if enough crooked, will develop a kink, weakening the spring.
Glock mags tend to have slightly shorter springs in relation to the magazine body than others, but made of thicker wire.
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Old January 25, 2015, 01:31 AM   #3
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Very interesting post, John. This is definitely one of the persistent issues in firearms discussions and, I would argue, one of the most important issues. Unlike caliber war arguments, which are fun but - as most rounds will do their job when placed on-target - fairly pointless, the spring issue matters a lot. Most people carry or store their guns for long periods of time.

I personally keep my magazines all loaded fully at all times. Beretta and MecGar magazines are better than most, so they likely pick up a lot of slack for me, but at the very least this information hammers home that prudent old chestnut: take your guns out for a test drive now and then if you're going to trust your life to them, and remember to maintain your gun!
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Old January 25, 2015, 04:56 AM   #4
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This is one of several reasons I always recommend revolvers to new shooters or non shooters. Many people start off with good intentions, and then don't practice or check their equipment for months or years at a time. If you leave a revolver loaded for even five or ten years, it will probably work fine. A semi-auto might not.
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Old January 25, 2015, 08:28 AM   #5
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Great Post!

The Glock spring performed well.

Assuming a similar performance from a +10% Wolff Gunspring, the spring would have as much force after being fully loaded for a year as a new Glock spring.
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Old January 25, 2015, 10:50 AM   #6
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Great information, and useful, too.

John KSa undertook these tests in response to discussions here where some participants said that ONLY working springs (i.e., their compression and release) wore them out, while others talked about other causes of spring failure.

Some participating here, including one Metallurgist (an engineer specializing in metals) and another engineer who made a hobby of studying spring technology, brought some expertise to the discussion. Those two discussed how materials changed with use -- and gave us a number of technical references and links to sites and articles, etc. Many participants here were still unconvinced -- primarily because of their experience with their personal weapons.

What the technical experts told us was that while cycling will degrade a spring, if it's well designed and made from good materials, that degradation may take so long as to be irrelevant. But they also told us that if the normal compression of the spring pushed the spring material to its elastic limit -- spring life would be more quickly degraded. Most involved in the discussion seemed to miss that point -- probably because their guns and mags never got to that elastic limit. The experts tell us that ALL MATERIAL, whether it's wood, plastic, rubber, rope, glass, or metal, etc., will degrade when pushed to it's elastic limit, and if held at that limit, it will degrade more quickly. Some materials, like aluminum, are very unforgiving; others like steel, can be flexed, stressed and returned without damage as long as they aren't flexed too far -- which may explain why we don't see aluminum springs.
Tappet springs in a car may compress and release many, many millions of times over an engine's life, but we seldom hear of them failing - they are designed so that the aren't pushed to their elastic limits. Recoil springs in a Rohrbagh R9, a very small 9mm semi-auto, have a design life of about 250 rounds (although I'm sure they'll last longer.) That design asks a very small spring made with less material designed to fit in a smaller space to do what larger springs do in larger guns.
For many guns, nowadays, made to shoot more rounds from smaller weapons, springs have become renewable resources. As is said in other cases, there's no free lunch, and something has to give...

John's test apparently pushes the Ruger spring closer to that spring's elastic limit than it does the Glock spring springs -- but in either case test results shows the degradation associated with storing those mags fully loaded did occur. It would probably take a metallurgist to tell us why the difference in performance -- but you can see that, in either case, leaving the mags loaded has an associated cost. These springs degraded and they weren't being CYCLED! They were just compressed and kept that way.

Wolff Springs (in its FAQ area) suggests downloading hi-cap mags a round or two for long-term storage. (I suspect the same is true for sub-compact mags, which are, for their size, also hi-cap mags.)

Last edited by Walt Sherrill; January 25, 2015 at 10:55 AM.
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Old January 25, 2015, 11:04 AM   #7
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We should make this a sticky. Good work.
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Old January 25, 2015, 11:20 AM   #8
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I inadvertently also did a mag spring test for a 1911.
A run of the mill 7 round gun show mag was left fully loaded for many years.
It was hiding out in the back corner of a shelf.
It must have been there for at least six years, possibly more like eight.
All rounds fired just fine and I still use it.
There's so many variables with mags, who manufacturers them and the parts they use, that trying to decide whether to keep them loaded or not might just be a very individual choice.
Judging from the results stated here, it probably would be prudent to either keep most of them unloaded, or rotate them regularly.
Maybe?
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Old January 25, 2015, 01:50 PM   #9
Walt Sherrill
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Quote:
Originally Posted by g.willikers
I inadvertently also did a mag spring test for a 1911.
A run of the mill 7 round gun show mag was left fully loaded for many years...
It was hiding out in the back corner of a shelf.
It must have been there for at least six years, possibly more like eight.
All rounds fired just fine and I still use it.
You're right: there are many variables.

There are many tales of WWII 1911s being left in drawers for 40+ years and pulled out, mags fully loaded, to function properly. The spring in a 1911 7-round mag has plenty of reserve and isn't near its elastic limit when fully loaded. Try that with a very-high-cap mag (maybe holding 33 rounds of 9mm in a Glock mag, or 17 rounds in a Ruger SR9, and you'll probably have a different experience.

I think the type of experience you described is why so many folks think that keeping mags fully loaded isn't an issue. And for many guns and mags, they're absolutely right. But with other guns and mag designs keeping the mags fully loaded can lead to relatively quick mag spring failure. I learned that some years ago with CZ hi-cap mags... replacing a number of hi-cap springs but never having to replace a 10-round mag spring. (Same spring -- used differently.)

Another participant here, who was in the Army NG, told of one NCO in charge of the unit's armory who stored all of the M9s with the slide locked back. All of the spring had to be replaced the following year. In normal function, recoil springs are at their elastic limits only briefly -- if at all -- but with some guns, if they're locked back for extended periods, they'd be at the elastic limit (i.e., springs almost stacked) they'll give up the ghost. (I'll bet you can't keep a Rohrbaugh R9 slide locked back very long without it having a big problem...)
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Old January 25, 2015, 03:16 PM   #10
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Some springs today aren't made of high carbon steel-they use things like work-hardened stainless steel. These materials degrade very quickly.
Unless gun springs are designed to be sacrificial, there is no reason they SHOULD degrade, other than: inferior material or heat treating, improper design, overheating (as in a fire), or corrosion.
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Old January 25, 2015, 04:44 PM   #11
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I wonder if this is just one of those things that we over worry and over obsess about.

How many have actually had an issue with mags failing from use or storage, and know for sure, that was the reason? Ive had mags fully loaded for years, that were forgotten and later found, and they worked just fine, when they were shot.

I have a bunch of Korean Glock mags that I shoot weekly, sometimes more than once a week, and have been doing it for about six plus years now. You always hear on the internet, that the springs (and not just the springs ) in these mags are crap.

A little over a year or so ago, I started having issues with function in the gun I normally use for practice, and since I use these mags all the time, they came under suspicion as a possible cause. This was also around the same time you were hearing a lot about extractor issues with the Glocks, which just clouded the issue.

I replaced extractors, as they seemed the likely cause, yet the problem remained. So I started looking to the mags. I replaced the springs in 10 of the mags with springs from Wolff. Still the problems remained.

Long story short, I figured out it was my brass that was the issue, or as best as I can tell right now, it seems thats the cause. I replaced the extractor with the one that was removed, and with factory ammo, it ran fine (still does). With my reloads, and lots that are starting to have a higher rate of brass failure, the problems come back.

I just wish now, I still had the original mag springs, as Im thinking that they were still OK. I have other mags, that are the same age (still with the original springs) and have seen the same use, but now have even more cycles through them, and they work just fine.

Just based on one use a week, and I often use them more than once a week, the first set of ten that had their springs replaced, were done at around 260 cycles, maybe a little less (thats figuring 5 years times 52 weeks). The ones still running the original springs, are now at around 320 cycles, and still seem to be fine.

I also had a couple of SMG's that were shot regularly for about 30 years. Those mags were loaded and unloaded constantly, and never once replaced. That includes a bunch of those cheap plastic SWD MAC mags.

We also used to shoot all manner of older "surplus" SMG's, using the original mags, many of which were from the late 30's early 40's, and they never seemed to have any issues. Who knows how many rounds they had through them. Im sure we probably put more rounds through them than the original users did too.

Now, on the other side of things, I have a CZ70 I got a number of years back, that came with a couple of mags that had springs that were shot. The gun would only function with three rounds in the mag. I ordered a bunch of spares, that were supposed to be new, and they had the same issue. I again got some replacement springs from Wolff, and the issue was instantly solved. Who knows what the real issue was, be it poor materials, or just use (the gun was about new, the mags had little wear as well). I guess we'll never know. Thats been the only gun Ive had that had issues I could say for sure, that were mag spring related.
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Old January 25, 2015, 05:14 PM   #12
Walt Sherrill
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Quote:
Originally Posted by Bill DeShivs
Unless gun springs are designed to be sacrificial, there is no reason they SHOULD degrade, other than: inferior material or heat treating, improper design, overheating (as in a fire), or corrosion.
So, you would have us believe that the Rohrbaugh R9 was designed so that the springs are INTENDED to lose functionality around 250-300 rounds, (or are made of defective materials)? And you would also have us believe that the recoil springs used in other smaller versions of larger guns (like some of the compact 45s, all of which recommend changing recoil springs far more frequently than is the case with the larger version of similar guns -- are intentionally built that way?

Recoil and magazine springs in smaller guns doing the same work in less space (and using less material) don't -- can't -- have the same spring life as the springs in larger guns shooting the same rounds. You make your claim above from time to time, and ask for proof. When it is provided time and again, sometimes by true experts -- you go silent. You don't refute the proofs. You just come back later with the same old claim: springs don't wear out unless they're poorly made, poorly designed, or made from bad material. While there clearly are poorly made, poorly designed spring made from crappy materials, those aren't the springs most of us encounter.

We've had this discussion before... Here's one of several examples: http://thefiringline.com/forums/showthread.php?t=460410 (We've had it in other places, too.) In the discussion in this link, you said, in response #18:

Quote:
Originally Posted by Bill DeShivs
So I want someone to, metallurgically speaking, explain to me all this "spring weakening."
John KSA went on, in response #19 to do cite examples with links. John's comment's about springs are always worth the time required. In my response (#25) I also included a link to an earlier, more involved discussion (in which you participated and took the same position as always.) That discussion included many technical links, some of which still work. (It's been a while, and websites change.) Bernieb90's contributions (response #41 if you click on mY link) are particularly interesting. A metallurgist gets involved either in this or a following discussion, and corroborates both John's and Bernieb90's points.

Properly designed springs made of good materials do wear out. Especially when smaller springs are needed to do more work or when they must be fit into smaller areas that force them function closer to their elastic limits during normal gun operation.

That's the part you continue to ignore: all guns and their springs are not created equal... and what is expected of gun springs -- their design objective -- may vary. In some gun designs SPRING LONGEVITY may be sacrificed to give the gun better or different functionality for a shorter period of time. It's like changing shocks or struts in a car! Some will last a long time, but they don't all live the same life and aren't all asked to do the same work. That seems to be the case with the Rohrbaugh recoil spring -- to get a longer-lived recoil spring the gun designer would simply have to make room for a longer, bigger spring -- and that would mean a BIGGER Rohrbaugh R9 -- that was NOT what the R9 was designed to be...
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Old January 25, 2015, 06:03 PM   #13
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Walt- what you just described are springs that are designed to be sacrificial.
Whether the springs are designed that way is irrelevant. The manufacturer knows the springs will be over stressed and recognizes it. I'd call that sacrificial. Whether it's "improper design" is up to the individual's interpretation.

I own, and have owned more guns than most people. I have worked on those guns and others. I can recall exactly ONE mag spring that failed by getting weak-a factory S&W 6906 magazine.
I repair antique switchblade knives. I make gun springs. I have made MANY hundreds of them-maybe over a thousand. I make 3-4 a week. Four have failed-all from the same piece of steel. I have seen many springs that are over 150 years old that work fine. I have never seen another spring-knife or gun, get weaker. I have seen them break from work-hardening.
Now, I admit that I'm a dinosaur. The only "modern" guns I own are Keltecs. The rest are traditional guns that are made of metal. No Glocks, SIGs, or HKs. The newest S&W I own is the 6906, so this may have some bearing on whence I speak. Maybe modern manufacturers are making springs out of spaghetti. I do know what I'm talking about when it comes to carbon steel springs.
All springs take an initial "set" when first compressed. They should not get "weaker." Some must, as there is so much talk about it. Until Wolff started selling springs, you never heard about replacing springs unless they were rusted or overheated (except for competition shooters). This was before the "modern" guns came out, too.
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Old January 25, 2015, 06:15 PM   #14
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Quote:
Originally Posted by Bill Deshivs
All springs take an initial "set" when first compressed. They should not get "weaker."
Quote:
Originally Posted by JohnKSa
The Glock 20 magazine has lost very little strength overall but the graph seems to have a slight but steady overall downward trend that apparently is continuing.
Are you implying that JohnKSa is faking his graphs? Do you not believe that he actually measured his spring performance over 400 days?
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Old January 25, 2015, 06:27 PM   #15
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I'm not implying anything. I'm telling you what I know to be fact.
I don't know what material John's springs are made of, whether they are properly heat treated, etc. I said that it's obvious something is happening to some people's guns. I also said that with properly designed and manufactured springs, it SHOULDN'T happen. I can guarantee you that I have more experience with carbon steel springs than most people on the planet.
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Old January 25, 2015, 07:21 PM   #16
Walt Sherrill
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Quote:
Originally Posted by Bill DeShivs
Walt- what you just described are springs that are designed to be sacrificial.
Whether the springs are designed that way is irrelevant. The manufacturer knows the springs will be over stressed and recognizes it. I'd call that sacrificial. Whether it's "improper design" is up to the individual's interpretation.
So, if they're designed to be sacrificial, why do you continue to say they're improperly designed? Or somehow poorly made. Or made from poor materials? I've said, time and again, that some of the new guns require springs to be renewable resources -- that is, they are made to work well for a time, because there is no free lunch: they are sacrificial springs. The Rohrbaugh R9 recoil spring is clearly one of them. Rohrbaught recommends replacing them every 250 rounds -- and I don't think they'll get rich from selling recoil springs. I've seen similar recommendations from some of the makers of compact and sub-compact .45s: recommended replacement after 500-1000 rounds rather than 3000-5000 rounds.

Quote:
Originally Posted by Bill DeShivs
All springs take an initial "set" when first compressed. They should not get "weaker." Some must, as there is so much talk about it. Until Wolff started selling springs, you never heard about replacing springs unless they were rusted or overheated (except for competition shooters). This was before the "modern" guns came out, too.
Horse hockey. Before modern guns came out, springs weren't pushed to the limits they're pushed to today. Springs do get weaker when pushed to their limits. Some aren't pushed to their limits. But some are and can be. JohnKSa's tests results show that. You continue to make claims that are refuted by tests, by experience, and by scientific analysis.

Will most guns continue to function properly without replacing springs frequently? Many certainly will. It's only the extreme cases that really cause problems. Like the Rohrbaugh R9, or some of the very high-cap mags.

Quote:
Originally Posted by Bill DeShivs
I own, and have owned more guns than most people. I have worked on those guns and others. I can recall exactly ONE mag spring that failed by getting weak-a factory S&W 6906 magazine.
I've heard of many magazines thrown out because they didn't function. Wonder why they didn't function? Wouldn't feed, etc. Think it might have been weak springs?

Quote:
Originally Posted by Bill DeShivs
I repair antique switchblade knives. I make gun springs. I have made MANY hundreds of them-maybe over a thousand. I make 3-4 a week. Four have failed-all from the same piece of steel. I have seen many springs that are over 150 years old that work fine. I have never seen another spring-knife or gun, get weaker.
And how many of THOSE springs are coil springs designed to fit in a very small gun that fires a very powerful round? Or in a high-cap magazine? Are your switchblade springs coil springs? You're talking about conventional springs that are designed for conventional weapons, arguably much older guns -- where springs simply can't be found easily. I believe that you've not had many problems with those springs. But they aren't the kind of springs that cause a lot of problems.

The point you overlook is that until relatively recently, when gun makers started much smaller guns in larger calibers or started making higher capacity guns with shorter and shorter barrels and shorter grips -- the areas where spring function really becomes critical -- it wasn't much of an issue.

While you make a lot of springs, I'll bet you're not asked to make springs for those newer kind of guns -- because those springs are readily available from other sources. You're probably asked to make springs for guns and knives that aren't available from most sources. You're providing a needed service.

Double-stack mags are still kind of new in the gun world. While the BHP had a 13-round double-stack in the late 30's, it was one of the few guns to do so for almost 40 years. SIG didn't start making double-stacks until the mid '70s (with the P226), and Glock and CZ were right there with them a year or two later. Double-stack mag springs do much more work than single-stack mag springs with each reload.

Quote:
Originally Posted by Bill DeShivs
Until Wolff started selling springs, you never heard about replacing springs unless they were rusted or overheated (except for competition shooters). This was before the "modern" guns came out, too.
That doesn't mean -- as you seem to suggest -- that until Wolff came on the scene springs didn't fail. Until Wolff started selling springs, folks did one of three things: 1) threw the mags away and got new ones, 2) folks just contacted the gun maker to get new mags or new springs, or 3) went to a gunsmith. Many still do that -- as not everybody knows to order their own springs from spring makers. (You read it here on the this forum with some frequency: "I just toss'em.") Wolff didn't really have a MARKET for their products until the very nature of guns began to change and guns started getting smaller and double-stack mags became a quasi-standard for the U.S. gun buying public.

Your experience and knowledge of spring making is certainly valid as far as it goes, but until you start making coil springs for Rohrbaughs R9s, for small sub-4" barreled .45 1911s, or for the hi-cap mags used in S&W M&P Pros, 17 round Ruger SR9s or 18-round CZs, your experience with spring durability may not apply to this discussion. All springs are not created equal.
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Old January 25, 2015, 09:32 PM   #17
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Walt- You seem to be arguing with yourself on most points.

The springs I make are leaf springs, for the most part. A leaf spring in a gun or automatic knife is put through much greater stress than any coil spring.
A spring is a spring. I have never seen one "get weak" (other than the one previously mentioned) but I have seen them work-harden and break. Have you EVER seen or heard of a D/A revolver hammer spring getting weak and failing?

I'm not saying it doesn't happen. What I'm saying is that it SHOULDN'T happen.
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Old January 25, 2015, 09:57 PM   #18
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Quote:
The springs I make are leaf springs, for the most part.
This test is exclusively applicable to coil springs.
Quote:
What I'm saying is that it SHOULDN'T happen.
Everything in design is a tradeoff. If you are trying for maximum capacity and minimum size then, as a designer, you may be willing to give a little in other areas--like depth of coil spring compression. It's a common tradeoff in the spring-piston airgun world and with well-known effects. More on that later.
Quote:
Whether the springs are designed that way is irrelevant. The manufacturer knows the springs will be over stressed and recognizes it. I'd call that sacrificial. Whether it's "improper design" is up to the individual's interpretation.
I think there are a lot of misconceptions about springs in the firearm world. Why that is, I don't know.

What I do know is that springs can weaken from being left compressed if they are compressed deeply enough. At about 50% compression, a spring will pretty much last forever assuming it's decent quality and made with some reasonable level of care. As the compression level increases past 50%, the longevity of the spring depends more and more heavily on the quality of the materials, the design of the spring and the quality control. As the compression level approaches 100%, it becomes a matter of fact that the spring is going to weaken to at least some level if it's left compressed for long periods--no matter how good the materials used, regardless of how well it's manufactured or how good the QC is.

Why this isn't accepted in the firearm world is a mystery to me. It's common knowledge in other fields.

http://www.airgunsofarizona.com/blog...ro-piston.html
“When you are using a mechanical spring in an airgun, you are just doing bad things to the spring,” Schultz adds. “A rule of thumb in engineering is that you don’t want to stress a spring past 50% compression to maintain reliability, but that doesn’t work in a spring gun. Instead, you compress the spring almost 100%. You take up almost all the gap between the spring coils to get ultimate performance, and that tends to weaken the spring. And if you leave it cocked, you’re taking some life out of the spring. So you use special materials and do special heat treatments to deal with that, but you’re basically fighting a losing battle.”
Magazines are a similar application in that they tend to compress the spring to, or nearly to, 100% compression.

At any rate, it seems moot. The test shows that leaving magazines fully loaded can weaken the springs. The weakening was noted in both magazines although it was much more pronounced in the Ruger mag than the Glock mag. At this point--given that I haven't range tested either spring-it's entirely possible that the weakening hasn't progressed to the point that it will cause failures, but that's another issue. Clearly leaving the springs compressed did weaken them.

That may surprise some folks in the firearm world, but it's not news to everyone. There are a couple of well-documented tests in the spring-piston airgun world that demonstrated that leaving metal spring-piston airguns cocked results in a weakening of the springs. In those two tests, every spring tested showed some weakening, and the weakening tended to increase the longer the springs were left compressed. It was true even in the case of top-quality custom replacement springs.
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I wonder if this is just one of those things that we over worry and over obsess about.
Those who are are missing the point. This isn't something to worry or obsess about, but it is something to be aware of.

We don't need to worry or obsess about tetanus, but we do need to be aware of it and how to deal with it constructively by taking preventive action.

In both examples, springs and tetanus, knowing that the problem does rear its head from time to time is actually quite valuable. It's only when we pretend that it's a non-issue--that it never happens--that we can get into trouble.
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Last edited by JohnKSa; January 25, 2015 at 10:03 PM. Reason: Changed initial comment to: "This test is exclusively applicable to coil springs."
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Old January 25, 2015, 10:07 PM   #19
polyphemus
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There are many tales of WWII 1911s being left in drawers for 40+ years and pulled out, mags fully loaded, to function properly.
Scovil magazine loaded over fifty years,good as gold.
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Old January 25, 2015, 10:17 PM   #20
Bill DeShivs
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Jim,
I'm well aware that over-compression of springs degrades them. It's common knowledge. Over-stress is the only thing that should "weaken" a spring.
Again springs are springs. Coil springs are simply long, thin leaf springs. Without over stress, any spring should last indefinitely. Without over-stress, no spring should weaken. They will, however break.
I do at times fail to take into account that makers will design guns that over compress their springs. This should NOT happen in full-sized guns-I would call that improper design. Tiny guns with sacrificial springs are understandable.
Your test showed that YOUR springs weakened from being left loaded. Not all springs do. I have guns that have been constantly loaded for 40 years or more that shoot just fine.
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Old January 25, 2015, 10:29 PM   #21
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Your test showed that YOUR springs weakened from being left loaded. Not all springs do.
I agree that in a design that doesn't heavily compress the springs, a good quality spring should not weaken when the magazine is left loaded. If, on the other hand, the spring is left at (or very near) 100% compression when the mag is loaded, it's very likely to weaken even if it's virtually perfect in every respect.
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I have guns that have been constantly loaded for 40 years or more that shoot just fine.
In all fairness, the fact that the magazines still function isn't evidence that the springs haven't weakened, it is only evidence that they haven't weakened enough to cause malfunctions. As noted, even with about a 27% reduction in spring strength, the Ruger P89 magazine will still lock the slide back when the slide is racked manually and I'm fairly optimistic that it will function in a range test even at only about 73% original strength. We'll have to wait until the test is completely over though to find out for sure.

It would surprise me tremendously if the G20 mag malfunctions in the final range test. It has certainly weakened (about 7% strength lost) but I doubt that's anywhere near enough to cause problems.
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