Spring Design

[BLR]

I think that will depend on the individual unit, but some commanders will like having pistols in racks locked back because it is immediately clear that they are unloaded, and the military really doesn't like loaded guns, because then you get accidental/negligent discharges with them, which in turn can lead to a commander's career terminating early. Far better to have prematurely worn out recoil springs, since they probably aren't going to be changed on a regular basis anyway.

Leaving the slide locked back/recoil spring compressed wont affect spring life.

At room temp, defect diffusion in steel is on the order of a nanometer per year IIRC.

[orionz06]

Leaving the slide locked back/recoil spring compressed wont affect spring life.

At room temp, defect diffusion in steel is on the order of a nanometer per year IIRC.

Random nerd question... What percentage of springs in the firearms industry would you guess at being properly designed thus adhering to the quote? I won't hold ya to it, I am just curious as I have often wondered if some springs weren't poorly designed.

[Jeep]

Leaving the slide locked back/recoil spring compressed wont affect spring life.

At room temp, defect diffusion in steel is on the order of a nanometer per year IIRC.

Bill: I'm no engineer, but is it possible that locking back a slide for a long time on an already worn recoil spring can result in more wear than that? I ask, because I have seen already-worn recoil springs seem to weaken after a prolonged lock-back. Perhaps it was just observer error, but the springs didn't work too well after that (admittedly it happened--or seemed to happen in Tokarevs, whose recoil springs wear out pretty fast).

[BLR]

Nope. What kills springs is the number of cycles. Not the duration of compression.

Assuming a consistent spring material. Crappier material = fewer cycles.

Flat wire springs last longer because they are loaded in bending, coil springs are loaded in torsion. And that is why I tell my students that differential equations IS something you will use later on in life.

[BLR]

Random nerd question... What percentage of springs in the firearms industry would you guess at being properly designed thus adhering to the quote? I won't hold ya to it, I am just curious as I have often wondered if some springs weren't poorly designed.

I have no idea. But let's just say, now that I got my cherry popped in this industry, I'm convinced no one has any idea as to what they are doing.

[JAD]

differential equations IS something you will use later on in life.
So are English.

Is it that black and white, or is it a tendency? Do flat wire springs load only in bending, or mostly in bending, some in torsion? It's a very interesting point that makes sense (at least as a tendency) and makes me want to work on very wee flat wire springs.

[BLR]

So are English.

Is it that black and white, or is it a tendency? Do flat wire springs load only in bending, or mostly in bending, some in torsion? It's a very interesting point that makes sense (at least as a tendency) and makes me want to work on very wee flat wire springs.

Heh. Anyway, Differential Equations, used in this context, is a singular subset of Mathematics. Like Organic Chemistry is a subset of Chemistry. Think of it as the "discipline and study of Differential Equations".

Rarely in life is there a truly simply loaded member. There is some bending in a wound round wire spring. There is some torsion in a flatwire. But not a significant amount.

[BWT]

I have no idea. But let's just say, now that I got my cherry popped in this industry, I'm convinced no one has any idea as to what they are doing.

This is what I suspected. Which is why I was surprised to find some 1911 springs that failed to slide lock after being compressed for 6 months when left empty for a few months and tried again locked back with complete consistency.

I had repeated the phrase that springs don't take sets so many times but yet my own experience contradicted that until a lightbulb moment came.

Properly designed springs operated within their range of design don't take sets from compression.

Crush a 1911 magazine with a multi-ton press. That will take a permanent change.

Most manufacturers I've ever heard of will not tell you what the spring wire they're using is.

[BLR]

This is what I suspected. Which is why I was surprised to find some 1911 springs that failed to slide lock after being compressed for 6 months when left empty for a few months and tried again locked back with complete consistency.

I had repeated the phrase that springs don't take sets so many times but yet my own experience contradicted that until a lightbulb moment came.

Properly designed springs operated within their range of design don't take sets from compression.

Crush a 1911 magazine with a multi-ton press. That will take a permanent change.

Most manufacturers I've ever heard of will not tell you what the spring wire they're using is.

Spring design is a compromise. It will always be. Some generalities: harder materials make better springs, as harder materials typically have a more defined elastic region. With metals, there is no such thing as a purely elastic region. A spring that "shortens" over time is generally preferred over one that breaks.

There are 3 types of Browning short recoil systems: the 1911/1935, the SIG, and the striker fired.
Correctly set up, the 1911/1935 design uses the "recoil spring" as a "reaction spring". By that, it's primary function is to feed a round and return the slide to battery.
The SIG design the hammer does nothing to retard the slide's reward velocity, which operates like a striker fired gun. This is my biggest complaint about the "over engineered" HKs and SIGs. This is partly because they tend to be DA/SA, but that's not as much as an excuse as some like to think.
Then there are the striker guns, which rely solely on the recoil spring and slide mass for operation. They are cheap to make, work best with polymer frames, and aren't exactly functional elegance IMO.

To tie that to the topic at hand, the 92 is more in the 1911 camp than the SIG camp, if memory serves me correctly (been a little while since I played with one). Which is why they are competitive in durability with the 226 and other aluminum frame guns with simple coil wire RSs, where the SIGs need something a touch more sophisticated.

YMMV, just an opinion, etc

[Bill Wilson]

What's all this spring stuff got to do with a Brig Tac ???

[JV_]

What's all this spring stuff got to do with a Brig Tac ???

Not much. I split the thread.

[BWT]

Spring design is a compromise. It will always be. Some generalities: harder materials make better springs, as harder materials typically have a more defined elastic region. With metals, there is no such thing as a purely elastic region. A spring that "shortens" over time is generally preferred over one that breaks.

There are 3 types of Browning short recoil systems: the 1911/1935, the SIG, and the striker fired.
Correctly set up, the 1911/1935 design uses the "recoil spring" as a "reaction spring". By that, it's primary function is to feed a round and return the slide to battery.
The SIG design the hammer does nothing to retard the slide's reward velocity, which operates like a striker fired gun. This is my biggest complaint about the "over engineered" HKs and SIGs. This is partly because they tend to be DA/SA, but that's not as much as an excuse as some like to think.
Then there are the striker guns, which rely solely on the recoil spring and slide mass for operation. They are cheap to make, work best with polymer frames, and aren't exactly functional elegance IMO.

To tie that to the topic at hand, the 92 is more in the 1911 camp than the SIG camp, if memory serves me correctly (been a little while since I played with one). Which is why they are competitive in durability with the 226 and other aluminum frame guns with simple coil wire RSs, where the SIGs need something a touch more sophisticated.

YMMV, just an opinion, etc

That's fascinating; thank you for always giving insights with us and your time.

[Maple Syrup Actual]

I have no idea. But let's just say, now that I got my cherry popped in this industry, I'm convinced no one has any idea as to what they are doing.

I would not have said this if you hadn't said it first but I have been convinced of this for a couple of years now. Pretty much since Gen 4 happened and the initial fixes weren't.

[Clobbersaurus]

I would not have said this if you hadn't said it first but I have been convinced of this for a couple of years now. Pretty much since Gen 4 happened and the initial fixes weren't.

I found this out a few years ago when I was playing with muzzle brake designs. The VAST majority of those that were putting out comps, brakes, whatever, had no idea how their devices worked. They simply made something they thought looked cool, "tested" it with a couple hundred rounds, maybe made a few tweaks, maybe not, then called it a day. I had the displeasure of talking to a few staff "engineers" that basically knew nothing about the concepts involved. I was no expert, but hell, you would think these guys would at least do some research before they started cutting steel.

That experience left me with a real nasty taste in my mouth.

[orionz06]

I found this out a few years ago when I was playing with muzzle brake designs. The VAST majority of those that were putting out comps, brakes, whatever, had no idea how their devices worked. They simply made something they thought looked cool, "tested" it with a couple hundred rounds, maybe made a few tweaks, maybe not, then called it a day. I had the displeasure of talking to a few staff "engineers" that basically knew nothing about the concepts involved. I was no expert, but hell, you would think these guys would at least do some research before they started cutting steel.

That experience left me with a real nasty taste in my mouth.

Why spend money designing things when there are people out there who will promote them without question?

[Maple Syrup Actual]

I found this out a few years ago when I was playing with muzzle brake designs. The VAST majority of those that were putting out comps, brakes, whatever, had no idea how their devices worked. They simply made something they thought looked cool, "tested" it with a couple hundred rounds, maybe made a few tweaks, maybe not, then called it a day. I had the displeasure of talking to a few staff "engineers" that basically knew nothing about the concepts involved. I was no expert, but hell, you would think these guys would at least do some research before they started cutting steel.

That experience left me with a real nasty taste in my mouth.

I remember that testing. That was really interesting. I assume you received a lot of hate mail from idiots.

Muzzle devices are the firearms lube of the firearms world.

[Jay Cunningham]

I thought firearms lube was the firearms lube of the firearms world?

:confused:

[Lon]

Once again, I feel like a dumbass when reading Bill's posts. Shoulda paid a lot more attention in science, math and physics classes. At least I understood enough to know that I've been teaching correctly when I discuss what wears out a spring faster.

[Maple Syrup Actual]

I thought firearms lube was the firearms lube of the firearms world?

:confused:

No, firearms lube is the game-changing ammo of the firearms world. Pretty different.

[Slavex]

Rarely in life is there a truly simply loaded member.
I dunno Bill, I've seen some of the members here after a few drinks....


(oh come on, it was right there).

Like many others I've believed the statement that springs don't set, for example with the slide locked back for a long period of time, or mags left loaded. Yet I've seen that happen with new guns and mags a few times, recoil springs that were apparently new, not able to return a slide to battery after only being left compressed for a couple weeks, or mags that once the first round was out, wouldn't lift the follower. Of course I've also seen a loaded mag from 1940-something or another, feed just fine, the live ammo that had been left in it since then. Maybe more care was spent on the engineering of those mag springs back then or maybe it's just pure luck?

[Chuck Haggard]

On some guns nowadays I have to wonder of the gun makers are cutting costs by using recycled paperclips to build springs.

We had several Mossberg 500s, as an example of what I am talking about, that were test fired, cleaned, loaded up, sat in a cop car rack for a year, and were then found to have mag springs too weak to feed the last couple of rounds out of the tube. I ended up having to replace every mag spring on every shotgun we had with Wolff mag springs. Problem was solved.

[Jeep]

Bill:

Help us non-engineers here. If springs can't take a set how is it that bad springs, such as Chuck is describing, seem to do exactly that? For a non-engineer, this is confusing.

[LOKNLOD]

Bill:

Help us non-engineers here. If springs can't take a set how is it that bad springs, such as Chuck is describing, seem to do exactly that? For a non-engineer, this is confusing.

Because of poor spring design, either geometry or material choice, results in a spring's normal range of motion taking it outside its elastic limits?

[BWT]

Because of poor spring design, either geometry or material choice, results in a spring's normal range of motion taking it outside its elastic limits?

This is what I believe the case is. Either the spring is not properly designed for its usage, compressions during usage cause the wear, or the spring material is inferior to what was intended.

ETA: I'll also disclaim I'm not an engineer. I only have what I've observed.

ETA 2: I think this is why we end up with 8 round magazines in 7 round bodies 1911 magazines forming a habit of not locking the slide back. The cutting edge 1911 8 round magazines usually have either a longer body, a newly designed spring (flat wire), or both.

[David Armstrong]

One some guns nowadays I have to wonder of the gun makers are cutting costs by using recycled paperclips to build springs.

We had several Mossberg 500s, as an example of what I am talking about, that were test fired, cleaned, loaded up, sat in a cop car rack for a year, and were then found to have mag springs too weak to feed the last couple of rounds out of the tube. I ended up having to replace every mag spring on every shotgun we had with Wolff mag springs. Problem was solved.
This. The issue of what wears out springs is one of the great non-issue arguments in the gun world (and others), IMO. Some springs wear out through repeated compression/relaxation cycles, some springs wear out simply by compressing them and leaving them compressed. You can argue for or against either one, but there are enough real-world examples of both to give plenty of evidence to support either position. As mentioned, it probably has far more to do with the material and construction of the spring than anything else. Your Mossberg example is a good one, as we had the same issue. Low number of cycles, long period of compression and the springs were toast.

[Urban_Redneck]

Bill:

Help us non-engineers here. If springs can't take a set how is it that bad springs, such as Chuck is describing, seem to do exactly that? For a non-engineer, this is confusing.

I find it hard to wound up about coil springs:rolleyes: I suppose I take their performance and low replacement cost for granted.



http://i245.photobucket.com/albums/gg59/Urban_Redneck_photos/Lang%20Barrels/DSCN0005_zpsa7d53ef9.jpg (http://s245.photobucket.com/user/Urban_Redneck_photos/media/Lang%20Barrels/DSCN0005_zpsa7d53ef9.jpg.html)

19th century techology

After 125 years of use and constant strain, one of these 21lb mainsprings broke. What would take to get similar longevity out of a modern coil spring?

[BLR]

Sure dude. Gimme a few minutes.

[littlejerry]

I have no idea. But let's just say, now that I got my cherry popped in this industry, I'm convinced no one has any idea as to what they are doing.

I'm an engineer and I agree with you. I've worked in medical, automotive, and now automotive child safety on the design side. Its surprising to me to see the amount of shade-tree "engineering" in the industry.

Sadly I think people confuse the ability to make something (and make it well) with the ability to design something from scratch to work well. I see this a lot in the firearms industry and recreational/hobby racing industry.

Rant/Example:
Sumdood with a machine shop decides to make widgets to sell for guns. He is a good machinist but has no credible education from a design standpoint.

He makes widget from titanium because... Blackbird!
He makes it to within +/- .00001 inches on all dims because... Precision!
He machines slots in piece to reduce mass but really just guarantee fatigue failure at 10^3 because....light weight!
He anodizes it, then tries to give it a TiN coating, then cerakotes it because... More!

Now specialty widget costs $100 and could have been a $10 cast aluminum component....

The forums catch on fire because sumdood gets retired Seal Team Six door-kicker to pimp the product as being the most precisely made, lightweight, and cool looking widget for AR15s.


Sumdood becomes AR15 widget "expert." Collectively the industry just got dumber.

/rant off.

[orionz06]

You forgot that some "SME" endorses it now for a few bucks and no one will actually listen to anyone truly qualified to have an opinion on it.

[BLR]

So, it's not really a material issue. 1095 is 1095, and that's the normal spring steel. Where things get fun is when we heat treat them and post process. Some springs are as drawn, some are tempered, some are passivated, some are stress relieved, and so on.

Take a really crappy as drawn spring, with no stress relief, shoddy heat treat, and so on, compress it, and it will undoubtedly not be the same length after sitting in the tube for 6 months. But that's not really a "spring."

Take that same application, use a good 1095 spring (stress relieved, and so on), put it in the same tube, and it will come out looking brand new.

Now, take a coil spring. There is a reason SIG uses a braided coil. Those 3 wires are much smaller in diameter than a single coil. The effect is that the spring, for the same total compressed changed in length will experience a much smaller total strain. Which puts the delta L more solidly in the elastic window for the steel. That's why the SIG RS lasts so long. Change over to a flat wire spring, and you go from a primarily torsion strain to a primarily bending strain. For the same application, your overall strain rate just went down allowing the spring to last much longer.

I'd put money on Chuck's springs going toes up because of improper heat treat/stress relief. Remember, coiling a spring is much easier when the spring isn't as spring-y :D

[Jeep]

Bill:

Thanks very much for the reply. To further translate for us former recreational-studies majors, does that mean that when we see what appears to be a spring failure from compressing the spring for too long a time, what we are in fact seeing is probably a spring that failed because it was improperly designed/manufactured?

In other words, is it a safe generalization that well-made springs don't get worn out after being compressed for a long time, but that can indeed happen with poorly made springs?

[Jim Watson]

I agree with David, it is not either or. Use things and they wear.

After all, one well known manufacturer routinely tells his customers to leave new magazines loaded for a week to set the springs enough to make them easier to load under a closed slide.

[BLR]

Bill:

Thanks very much for the reply. To further translate for us former recreational-studies majors, does that mean that when we see what appears to be a spring failure from compressing the spring for too long a time, what we are in fact seeing is probably a spring that failed because it was improperly designed/manufactured?

In other words, is it a safe generalization that well-made springs don't get worn out after being compressed for a long time, but that can indeed happen with poorly made springs?

Wouldn't get an argument from me on that.

It matters because ignorance is not bliss. Ignorance is expensive, embarrassing, and often painful.

[CCT125US]

Bill, would you say HK produces high quality mag springs? I recall you making mention of HK being a "magazine company". My experience is limited to P30 / good and USP .45 / bad.

[David S.]

....... nm

[Jeep]

It matters because ignorance is not bliss. Ignorance is expensive, embarrassing, and often painful.

Indeed. Sometimes I think that I'm a living lesson of that fact.

In any event, thanks much for taking the time to answer my questions, which has made me slightly less ignorant on the subject.

[dsa]

So who makes the best quality spring?

[jh9]

I agree with David, it is not either or. Use things and they wear.

After all, one well known manufacturer routinely tells his customers to leave new magazines loaded for a week to set the springs enough to make them easier to load under a closed slide.

So to start with something that I think most everyone knows and agrees on (but to make sure the last paragraph in this post has context): Springs can be over-comprsessed. Doing so changes the properties of the material.

It might be a case of the involved parties not knowing exactly what the limits of the spring are, and by leaving them overcompressed for a time the changed properties of the spring are now in line with what they should have been from the start (given the other magazine parameters). But unless the person specifying the spring spent years getting the right to put "professional engineer" on their business card, it's often easier to just pick a spring and try it, jiggle the handle (parameters) and try it again until you get something that works rather than do it up right from the beginning. The former takes some doing (and luck). The latter takes 4-8 years in school and a decade or so on the clock. (Which makes it expensive, for one spring in one part.)

[luckyman]

Geez, it's been 25 years since I did any real mechanical engineering and actually spec'd out springs, but the physics of something like a flat wire compression spring aren't too weird; and the first thing you would normally do would be to confirm the design is such you couldn't compress it past the material's elastic limit. Because bad things then typically happen then. (ETA: err, that's an exaggeration. That would probably be the 3rd thing you would do). So failure modes are almost always material treatment issues, material defects, or the number of compressions. Unless they don't actually do any real engineering, which I would doubt because of liability issues?

Unless I've lost too many brain cells and forgotten something important, which is definitely possible :-).

[Slavex]

so based off of what we've learned about springs so far, what would one's opinion be of someone cutting down springboxes on slides to get a slide that travels further on the way back? I'm thinking unless specialized springs were used to handle this "stroking" that we'd expect failures of the springs more quickly as they are being compressed passed their designed limits.

[LOKNLOD]

so based off of what we've learned about springs so far, what would one's opinion be of someone cutting down springboxes on slides to get a slide that travels further on the way back? I'm thinking unless specialized springs were used to handle this "stroking" that we'd expect failures of the springs more quickly as they are being compressed passed their designed limits.

If I'm thinking of the right part as the springbox, it's possible that the spring isn't compressing any further, it's just that the slide is further back when it reaches that max compression. You'd be changing the uncompressed length, but not necessarily the maximum compressed length.

[ST911]

One some guns nowadays I have to wonder of the gun makers are cutting costs by using recycled paperclips to build springs.

We had several Mossberg 500s, as an example of what I am talking about, that were test fired, cleaned, loaded up, sat in a cop car rack for a year, and were then found to have mag springs too weak to feed the last couple of rounds out of the tube. I ended up having to replace every mag spring on every shotgun we had with Wolff mag springs. Problem was solved.

Same experience here. Mossberg OEM springs in the 500/590 sucked. Aftermarket was the cure.

[Clay]

Same experience here. Mossberg OEM springs in the 500/590 sucked. Aftermarket was the cure.

Wolff Xtra Power springs were the way to go. That's what I always put in my 500, 590, and 870's. Seems like they were about six inches longer to start with.

[Slavex]

I learned the term "spring box" on here, from Todd I think, but just to make sure we are talking about the same part, it's the part of the slide the recoil spring and guide rod go into. Akai has been selling "stroked" guns for awhile now and unless I'm missing something, those springs must be compressing more than ones with standard length springboxes, right?


If I'm thinking of the right part as the springbox, it's possible that the spring isn't compressing any further, it's just that the slide is further back when it reaches that max compression. You'd be changing the uncompressed length, but not necessarily the maximum compressed length.