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Old April 4, 2013, 08:35 PM   #26
Walt Sherrill
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I'm a structural engineer. The failure mechanism for springs would be fatigue. Springs are made and designed to be compressed, that's what they're good for. In order to induce fatigue you must compress and decompress springs many times.
You can also induce fatigue in a spring by pressing/pushing that spring FARTHER than it's designer meant it to be compressed, or by keeping it in that compressed state at it's design limits (or beyond). Problems generally arise only at or near that elastic limit.

Other engineers participating here in earlier versions of this discussion, including one who spent some time investigating spring design and behavior, citing in the process a number of technical links (including a few shown below), have addressed this aspect of metal fatigue. It's a problem that occurs near what Wolff Springs call the "elastic limit" and a lot of springs never get NEAR that limit, so they work and work and work... just like Tappet Springs in a car's engine.

Here are some of those links:
Ex:
http://www.spring-makers-resource.ne...les/fig_37.pdf

Also:
http://www.spring-makers-resource.ne...ng-design.html
http://www.spring-makers-resource.ne...g-designs.html

And
http://en.wikipedia.org/wiki/Elasticity_(physics))
http://en.wikipedia.org/wiki/Plasticity_(physics))
http://en.wikipedia.org/wiki/Viscoelasticity
http://en.wikipedia.org/wiki/Creep_(deformation))

Just a snippet:

Taken from http://en.wikipedia.org/wiki/Viscoelasticity
"All materials exhibit some viscoelastic response. In common metals such as steel or aluminum, as well as in quartz, at room temperature and at small strain, the behavior does not deviate much from linear elasticity. Synthetic polymers, wood, and human tissue as well as metals at high temperature display significant viscoelastic effects. In some applications, even a small viscoelastic response can be significant. To be complete, an analysis or design involving such materials must incorporate their viscoelastic behavior. Knowledge of the viscoelastic response of a material is based on measurement"
Many springs in magazines aren't pushed near that elastic limit -- and it's most often only in the high-cap or compact (sub-compact, etc.) mags that designers force the springs to do things that aren't normally asked of springs.

As others have noted, letting springs REST won't restore lost power. Rotating mags won't prolong their collective lifetimes except from NOT being worked. Springs lose power because the internal structure of the spring metal has changed. Coil springs are more inclined to weaken than break, because the work is distributed more uniformly over the entire spring material than with leaf springs.


.

Last edited by Walt Sherrill; April 6, 2013 at 07:39 AM.
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Old April 4, 2013, 09:34 PM   #27
Kevin_d77
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Guess I should have said "typical spring failure is do to fatigue from compression and decompression in properly designed springs."

You are correct, there are other ways to ruin springs. But a magazine that is designed properly should have excess compressive capacity built into the spring, a safety factor if you will, that should exceed normal compressive loading expectations.

It is an interesting topic indeed. Gotta love physics

http://www.spring-makers-resource.ne...les/fig_37.pdf

If you notice, these losses occurred at temperatures over 200 degrees F at over 100 hours. Extreme events and conditions will make any metal behave differently than at room temperature.

Article outlining the various materials used in magazine springs: http://www.whitesounddefense.com/pag...Materials.html

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Old April 4, 2013, 09:51 PM   #28
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It isn't magic. To some, a magazine that holds another round or two is more important than staying within the reliable range of motion the spring is capable of sustaining.
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Old April 4, 2013, 11:27 PM   #29
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Springs are simply another mechanical device. And Just like every other mech. devise out there you have the occasional failure.( metallurgy is not a perfect science ) "Normally" mag springs will hold up fine left fully loaded. That being said I have had a couple give out on me over the years. For Carry guns I believe it is prudent and cheap insurance to change out your mag springs at least every 2 years. Good Luck
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Old April 5, 2013, 12:32 AM   #30
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Ok Skitter here is my personal experiance for what it's worth. When I was working Overseas as a contractor I was issued both an M4 and a M9. About once a month we had to download our magazines for a round count.

Some of the mags that I had were like what you described. All I did was download the mag. Pull the spring out and stretch it out. Put it all back together. Reload and all was well.

Now this may only be a temporary fix. But it should get you by until you can get some new springs ordered and installed.
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Old April 5, 2013, 07:14 AM   #31
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First thing on my list after next payday is buying some mag springs, about $8 a pop.
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Old April 5, 2013, 10:46 AM   #32
Walt Sherrill
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Quote:
Originally Posted by Kevin D77
You are correct, there are other ways to ruin springs. But a magazine that is designed properly should have excess compressive capacity built into the spring, a safety factor if you will, that should exceed normal compressive loading expectations.
I added the underlining, above. That's a good point, and that's why most mag springs won't fail.

The problems arise when they try to stuff 17 rounds into the same space they once stuffed 10 or 15, or when the gun makers try to 8 rounds into a compact mag that probably would do better with 6. Then "normal compressive loading expectations" go out the window.

Over the past couple of years, gun designers have been making smaller guns do more, and bigger guns do more too. In doing that, they've pushed smaller barrels into smaller frames, and asked those guns to handle the same recoil. They've also made small gun have almost the same capacity as full-size guns. Springs are what gives. They have become, for those guns, at least, a renewable resource.

If you compare recommended cycle lives (shot counts) on recoil springs for the sub-compacts, they're much shorter than the guide lines for full-size guns. If it was primarily "cycling" the springs that led to a shorter life, that should NOT be necessary (i.e., shorter life for recoil springs in compact guns). But since smaller springs are being asked to do as much work as larger ones, something has to give. Spring life, it appears.

Your point is that a properly designed spring properly used should live a long life. Good point.... and why we keep hearing about WWII 1911s, found fully loaded, but stored for 40-50 years, working like new. There was reserve built into those 7-round springs.

I have been a CZ enthusiast for years. The standard 75B first came with a 15 round mag, and they later (during the ban) sold a bunch with 10-rounders. CZ Mags now can be had in 10, 15 and with a different base and follower, 16, 17 18+ round capacities. They all seem to use the same spring.

The 10-rounders will arguably last forever -- I've never had to replace one. Most the the 15 rounders will do pretty well, but the rest of them may not live as long, because the same spring is doing more work for the same number of rounds fired. Fully loaded, that 17-round mag is holding and trying to lift 7 more rounds than a 10-round mags -- {B]it's working even when it's not moving[/B]. If that work occurs when the spring at it's elastic limit (what you might call normal compressive loading expectations), all bets are off.

The engineer that posted the links in my response -- you can probably find the whole chain of messages if you patiently search -- noted that degradation occurs NOT just at high temperatures. And members here who know about air guns affirm that leaving a spring-powered air gun cocked is a sure way to kill the springs. There's a lot of folks who shoot air guns. Talk with them if you can. Some gun springs are now intended/designed to be disposable and NOT last the life of the gun.

.

Last edited by Walt Sherrill; April 6, 2013 at 07:02 AM.
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Old April 5, 2013, 11:07 AM   #33
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I did want to apologize for my earlier snapiness, I had been floating on the forums all day and was getting tired of every thread I had been reading dissolving into a ******* contest. I was looking for factual information and fact based opinions, first couple posts threw me off cause they had NO bearing on what I was experiencing. Thank you all for the information and I think my brain is now loaded pretty well with mechanics of springs

Conclusion: Yeah I need to replace the springs, and now I know how to tell if they are getting weak or not. In my wifes PX4 mags the last 4-5 rounds are near impossible to load without the mag loader that came with the gun. I noticed the same on my Cougar with the 11rd capacity.

Am I correct in assuming the 11rd .40S&W mags in my cougar are also considered high capacity and in that regard need to be left 1-2 rounds short of loaded in storage?
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Old April 5, 2013, 02:00 PM   #34
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Quote:
Some of the mags that I had were like what you described. All I did was download the mag. Pull the spring out and stretch it out. Put it all back together. Reload and all was well.

Now this may only be a temporary fix. But it should get you by until you can get some new springs ordered and installed.
I've heard that same story, from a guy who was in the desert twenty years ago. Stretching the spring will work temporarily, as in, it might last for a day.
I've seen guys stretch springs for competition use, and they go in the trash after the match. I'd rely on a stretched spring only long enough to drive to the spring store!
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Old April 5, 2013, 06:27 PM   #35
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Stretching springs is a short-term fix. It degrades the damaged springs even more. If you stretch them, do it when you have no options.

If all you had to do with a worn coil spring was to stretch it, there wouldn't be much of a market for replacement springs... But there is.

Skitter: the 11-round mags are functionally equivalent to hi-caps, and there's not much reserve left when the mags are fully loaded. They seem to hold up pretty well. Downloading a round or two can't hurt, for long-term storage.

(I generally leave my mags UNLOADED except for the gun in the bed-side gunsafe, and the one I carry -- when I carry. That's a sub-compact, so I try to shoot it now and then, to see that it's working alright.)

Last edited by Walt Sherrill; April 5, 2013 at 06:34 PM.
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Old April 5, 2013, 07:07 PM   #36
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I only have the 1 pistol (the other is the wifes), and it gets shot about once a month as funding and ammo are available. As most people say anything over 5 rounds is overkill for self defense, so I should be good knocking the mags in mine back to 8 rounds
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Old April 5, 2013, 07:10 PM   #37
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Quote:
Posted by Skitter:
As most people say anything over 5 rounds is overkill for self defense.
"Most people"? I seriously doubt that!
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Old April 5, 2013, 07:19 PM   #38
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How many articles or posts have you read where a person had to empty a whole clip of 17rds into an intruder to get them to stop?
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Old April 5, 2013, 07:47 PM   #39
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Quoting Walt:

Quote:
The engineer that posted the links in my response -- you can probably find the whole chain of messages if you patiently search -- noted that degradation occurs NOT just at high temperatures. And members here who know about air guns affirm that leaving a spring-powered air gun cocked is a sure way to kill the springs. There's a lot of folks who shoot air guns. Talk with them if you can. Some gun springs are now intended/designed to be disposable and NOT last the life of the gun.

Its been just over a year since the I posted those links in the following post found here. http://thefiringline.com/forums/show...ep#post4469935

Quote:
Stress over time does cause relaxation/load loss/creep.

If designed properly, it will not impact the function.

Ex:
http://www.spring-makers-resource.ne...les/fig_37.pdf
Read post 41 in Walts post/reference thread

Also:
http://www.spring-makers-resource.ne...ng-design.html
http://www.spring-makers-resource.ne...g-designs.html
http://www.spring-makers-resource.ne...ce_summary.pdf

And
http://en.wikipedia.org/wiki/Elasticity_(physics))
http://en.wikipedia.org/wiki/Plasticity_(physics))
http://en.wikipedia.org/wiki/Viscoelasticity
http://en.wikipedia.org/wiki/Creep_(deformation))

Just a snippet:
Taken from http://en.wikipedia.org/wiki/Viscoelasticity
"All materials exhibit some viscoelastic response. In common metals such as steel or aluminum, as well as in quartz, at room temperature and at small strain, the behavior does not deviate much from linear elasticity. Synthetic polymers, wood, and human tissue as well as metals at high temperature display significant viscoelastic effects. In some applications, even a small viscoelastic response can be significant. To be complete, an analysis or design involving such materials must incorporate their viscoelastic behavior. Knowledge of the viscoelastic response of a material is based on measurement"

Its really not a question if.... its a question of will it impact the function.

Walt is doing a great job explaining it. Simply put, the further you compress a spring into its elastic range, the quicker it will degrade.

For reference, a valve tapit spring is only compressed around 25% of its length. It will withstand millions of cycles. Mag springs are compressed a heck of a lot farther than that.

If the # cycles was the sole predominate factor, we'd all be replacing recoil springs at a rate of 10 to ~20 times the rate of replacing mag springs and that assumng only 1 mag was used with a capacity of 10 to ~20.

Its just not that simple.
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Old April 5, 2013, 08:07 PM   #40
Skitter
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Looks like instead of starting a ******* contest I started a severe physics debate...
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Old April 6, 2013, 07:54 AM   #41
Walt Sherrill
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Quote:
Originally Posted by Skitter
Looks like instead of starting a ******* contest I started a severe physics debate...
Yup. You're also helping to put one of the gun world's "old wives tales" to rest -- that springs only wear out with use (cycling).

As all of this notes, it really depends -- on the gun, the way it's used, and how the springs are asked to perform their duties. All guns and gun springs don't do it the same way.

Everyone cites their experience and considers that experience TYPICAL. (It is -- for THEM!) The spring life of a full-size gun (recoil, magazine) tends to be different than the spring life of compact guns, for example.

Quote:
Originally Posted by Skitter
I only have the 1 pistol (the other is the wifes), and it gets shot about once a month as funding and ammo are available. As most people say anything over 5 rounds is overkill for self defense, so I should be good knocking the mags in mine back to 8 rounds
None of the stuff I posted argues for reducing the number of rounds in the gun when it's being used (carried, kept in the safe for home defense, etc.) -- only for reducing round counts when the mags are being stored for extended periods. That's because in some cases -- mostly hi-cap and sub-compact guns -- the "stored" mags are still working if they're loaded and the springs are almost fully compressed. In those situations, downloading a round or two (in a stored mag you're not likely to use immediately) makes sense.

In your case, keep the mags most likely to be used in an emergency fully loaded, and check them out when you go to the range. As long as you get good function, don't worry about them. It might be good to have a set of spare springs stashed away, however, for when you start to notice feeding problems during a range trip.
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Old April 6, 2013, 09:16 AM   #42
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.....

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Old April 6, 2013, 09:43 AM   #43
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springAnimation.gif

Here is a gif that illustrates that stress increases as the spring cycles deeper into it range; Abeit, overly simplified.

Last edited by danez71; April 6, 2013 at 09:54 AM.
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Old April 6, 2013, 09:53 AM   #44
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I understand exactly how springs work. Thanks for the animation.

Do you really think the engineers that designed them didn't take into account the maximum required compressive strength of a spring? If that is indeed the case then how could you trust them to design any other part of the gun?

There are many variables at work here. I tend to believe that a spring will operate properly when compressed within its limits of design and that the constant cycle of gaining and releasing energy is what causes the damage. But you continue to believe what you believe.

Also, in your picture, notice the spring is compressed to its maximum point and it is no where near the yield stress of the steel. So under static loading, as shown directly from your picture, the spring will not reach yield.
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Old April 6, 2013, 09:54 AM   #45
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HkGuNs said:
Quote:
Keeping your magazines full absolutely will wear them out, contrary to some rather loud Internet opinions.

I am sure it will be but a few minutes before the minions start repeating the Internet gun forum lore to the contrary! But fear not, this topic comes up every six months and is usually good for at least three additions to my ignore list.I hear them coming, even now........

Absolutely, change out those springs.
That seems very childish.
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Old April 6, 2013, 09:58 AM   #46
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Quote:
Originally Posted by whip1
HkGuNs said:
Quote:
Keeping your magazines full absolutely will wear them out, contrary to some rather loud Internet opinions.

I am sure it will be but a few minutes before the minions start repeating the Internet gun forum lore to the contrary! But fear not, this topic comes up every six months and is usually good for at least three additions to my ignore list.I hear them coming, even now........

Absolutely, change out those springs.
That seems very childish.
And yet there are still people arguing that what I have had happen cannot be possibly true because springs just don't weaken from sitting overly compressed. Somehow, in both of my wifes 17rd mags, they were kept fully loaded for 4 years without being unloaded or shot, and the springs wont hold up the last 1-2 rounds... That would signify that in MY mags, the springs did weaken, despite how many people want to argue to the opposite...
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Old April 6, 2013, 10:02 AM   #47
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Forget it. I bow out.

Skitter sorry you got bad mags.

I trust mine loaded but do whatever makes you feel most comfortable.

Have a great weekend people.

Last edited by Kevin_d77; April 6, 2013 at 10:08 AM.
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Old April 6, 2013, 11:03 AM   #48
danez71
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Quote:
I understand exactly how springs work. Thanks for the animation.

Do you really think the engineers that designed them didn't take into account the maximum required compressive strength of a spring?

This isnt a pass or fail issue. Its a rate issue.

In an effort to put more rounds in a smaller space, engineers have implemented deisigns that allow the springs to compress deeper into their elastic range, thus sacraficing spring life.

Springs are a consumable item. The real issue is the rate of consumption; not a works/doesnt work - pass/fail - consume/not consume issue.


A 13 round fullsize BHP mag may last 50k cycles or 20yrs compressed storage life.

The tiny subcompact 9mm Rohrbaugh is 6 round but since its a single stack will take up relatively close to the same linear space as the 13 round BHP (for illustrative purposes).

The Rohrbaugh mag is roughly 1/2 the length of the BHP mag even though they both need roughly the same amount of linear mag spring travel.

Rohrbaugh recommends changing after only 200 rounds. Rohrbaugh themselves down graded from 500 to 200 rounds.

Thats due to the rate of spring degradation as a result of it being compressed deeper into the springs elastic range.



Quote:
If that is indeed the case then how could you trust them to design any other part of the gun?[/

Simple. If they designed it to work for 200 rounds and it does, then their design worked and they seem to know what they're doing. If they designed it to last 50k cycles and it only lasts 200, thats another story.



Quote:
There are many variables at work here. I tend to believe that a spring will operate properly when compressed within its limits of design and that the constant cycle of gaining and releasing energy is what causes the damage. .

So you acknowledge there are many variables but choose to ignore that degradation increases as its compressed deeper into its elastice range as one of the variables and choose to only focus on cycling....

A spring operates properly as compared to what the design engineer designed. Not yours, or mine, definition of "properly". If Rohrbaugh made a design that only lasted 200 rounds, their design is "properly" working.


You also have to keep in mind that none of the gun mfgrs say to store your gun loaded; hence the reason everyone talks 'round count life' and 'never compressed storage life'.


As I said above, If the # cycles was the sole predominate factor, we'd all be replacing recoil springs at a rate of 10 to ~20 times the rate of replacing mag springs and that assumng only 1 mag was used with a capacity of 10 to ~20.


But we're not replacing them at that rate which clearly indicates there are other predominate factors. Enter subject: Elasticity range.



Quote:
But you continue to believe what you believe.
Sure thing. To recap, I'll continue to believe what science has proven and you can continue to acknowledge, but ignore, other variables; such as the range of elasticity for a given spring.
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Old June 7, 2013, 03:08 PM   #49
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Just about anything that is compressed for a long period of time will eventually begin to hold the compressed shape.
What I would do before changing out the springs is disassemble the magazine and stretch out the existing spring, then put it back together, load it, and see if the cures your loose ammo problems.
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Old June 7, 2013, 05:29 PM   #50
Walt Sherrill
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Quote:
What I would do before changing out the springs is disassemble the magazine and stretch out the existing spring, then put it back together, load it, and see if the cures your loose ammo problems.
That will work for a short while, and it's a good short-term solution as you wait for replacement springs to arrive, but won't work over the long-term. If its an emergency, it's a good emergency step. Otherwise, you're just speeding up the spring's demise. Mag springs lose power (sag) because the structure of the metal has been subtly damaged, and stretching will only damage that structure further.

Spring don't get stronger with rest, and they don't regain lost power by being stretched. Rotating mags doesn't prolong the life of mags -- it just spreads the wear over a larger number of magazines -- which is fine. But, over time, rotating the mags doesn't save you anything -- it just postpones the need to buy new mags or mag springs. Over the long run, you'll use the same number of mags or mag springs, and nothing is gained. (Given inflation, it might actually cost you more -- if you postpone buying the mag springs.)


.

Last edited by Walt Sherrill; June 7, 2013 at 05:46 PM.
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