[WonderNine]

The sales pitch is that chrome silicon wire is 1000X more resistant to losing its "memory" compared to typical spring steel. Perhaps this will be the end of "weak" mag/gun springs.

I received a chrome silicon wire spring for a 30 round AR-15/M-16 mag in trade last year from a guy who makes these springs, this is how I first found out about them. He claims the army is switching to these springs. Now I see them available on Gunbroker the past few months.

I have noticed that Pro Mag is now using chrome silicon wire springs in their EXCELLENT 10 round Mini-14 magazines.

My attempts to contact Mec-Gar to find out if they will be switching to csw for their mags has been unsuccessful, they don't seem to answer their phone anymore and they never did send out my replacement parts :rolleyes:

Has anybody seen csw in any new guns they purchased recently?

I'd like to hear people's thoughts on this new development that doesn't seem to be getting alot of press....

[WonderNine]

Hmm....I guess everyone's more interested in Kill Bill....:(

[AJ Dual]

Yes they are...


And the Temporal Continuity Comission would very much like them back.

They weren't supposed to be invented untill 2016.
Sorry, slow day at work. Feelin' punchy... :D

Pictures dumped, OT and spurious waste of bandwidth...Sam

[WonderNine]

I think I would have gotten more serious replies if I had posted this on Disney.com.

[Pendragon]

never heard of them - but it sounds really cool.

The springs are the weakest link in making a gun that lasts a really really long time.

I remember reading about tricky alloys in the 1980s that you could form to a shape, then bend them all up and when you heated them, they would pop (sometimes violently) back to their original shape.

I wish I knew more about metal, its very interesting.

What is the role of the silicon? is it part of the alloy or just a coating?

[Jeff White]

Wondernine,
there is no MWO (Modification WOrk Order) to change the springs in M16 magazines. I don't know if they have changed the standards for the springs in new magazines though.

Jeff

[AJ Dual]

Okay...

Here, to make up for it:

Chrome Silicon springs are certainly what I'd want if a huge gun ban came down and I had to cache weapons & mags, or couldn't count on ever getting legal spare parts again. I guess they've been using CS springs in engine valves for awhile. I'd guess that they get compressed a heck of a lot more than any firearm spring ever does, even full-auto.

Anything that enhances a firearms durability does have a potential upside for the future generations that inherit them. I do seriously wonder, political issues notwithstanding, how many 20/21st century arms will still be servicable, and in what condition 120 years from now, compared to arms from 1883.

[mete]

Are you talking about chrome silicon "steel" ? If so it's probably 9254 -a chrome-silicon spring steel - .54% Carbon, .70% chrome, 1.4% silicon . Nothing new , a good spring steel and if heat treated well will work . Sounds like they just decided to hype it up a bit for those who never heard of it .

[Skunkabilly]

Wondernine, what's Kill Bill? Like Killbilly? :confused:

I have a set of strings for my guitar that have Goretex on them. Supposedly they last longer and resist corrosion, etc. etc. etc.

Is this supposed to be on the same principle?

[WhoKnowsWho]

I remember seeing an ad about high chrome content gun springs... can't remember the company name or web site though... Promised no spring set and longer lasting memory of the original shape.

Pick up an American Handgunner if you have one handy, small side ad.

[whitebear]

WonderNine -

Nowlin Guns in Claremore, Oklahoma, is using chrome silicon springs in their 1911s, and you can also buy their Multi-Spring Recoil Systems for Glocks and 1911 which feature chrome silicon springs.

Their guns get really good reviews!

[WhoKnowsWho]

Ah ha, www.ismi-gunsprings.com the site is broken though... read more here at http://www.topglock.com/catalog/recoil.htm about the "ISMI difference"

"ISMI premium springs are manufactured exclusively with certified aerospace specification alloys; stainless or chrome silicon. Then our springs are heat treated, shot peened and stress relieved after winding to enhance performance and durability. Our springs utilize the same design and manufacturing technology as used in Indy Car and Formula One racing. In a typical 500 mile race, a valve spring in an Indy Car will go through more than 2,500,000 compression cycles. Consideration of factors such as modulus, wire diameter, mean diameter, active coils, total deflection, spring relaxation, maximum service temperature, and operating environment; results in you having modern spring technology available for your pistol."

Etc etc...

[WonderNine]

Okay, I just hooked up my scanner. I don't have any webspace to upload files to right now, so I just used an OCR program to show you the sales pitch I got. Oh duh, I just remembered I can attach files here. Well anyways, here it is:


==================================================


MURPHY RESEARCH

Next Generation AR-15 Magazine Springs:

Most AR-1 5 magazine springs are made of music D-wire, also known as music string wire. It is good wire. Barry Manilow has a piece of it in his piano. You judge the results.

Government contract magazine springs are made of 17-7 stainless wire. It is more corrosion resistant than music wire. So far so good.

There is one fly in the ointment (isn’t there always?). After repeated or continuous compression these springs lose memory of their expanded state (i.e. take a set), and lose much of their ability to expand. Your magazine then exhibits a decreased or absent ability to feed. This is an annoyance on the range, but flat out sucks in the middle of a firefight.

Murphy Research Next Generation magazine springs are made of chrome silicon wire. Chrome silicon wire has 1000 times more memory than music wire or 17-7 stainless wire. They are just not inclined to take a set. You can load a magazine with a Murphy Research Next Generation spring and it will reliably feed after twenty years.

We apply a zinc phosphate (Parkerzing) finish to our springs. That provides 72 hours of corrosion protection in a salt spray environment Don’t store your magazines on the deck of a boat on the ocean for more than a three-day weekend.

Murphy Research Next Generation magazine springs. Load your magazines, and your next generation can use them with confidence.

Oh, by the way, forget about downloading your magazines to 28/18 rounds. Murphy Research Next Generation magazine springs will feed 30/20 rounds all day long without a belch.

====================================================

[WonderNine]

Wondernine, what's Kill Bill? Like Killbilly? :confused:

You need to get out more my tactical friend. :D :p

[atek3]

good one andrew :)

atek3

[Jeff White]

Wondernine,

It's a good sales pitch, but it's just that, a sales pitch. Any spring only has so many compressions and contractions in it before it wears out. I have USGI 20 and 30 round magazines that I'm sure have 10s of thousands of compression/expansion cycles in them and the springs work fine. The aluminum feed lips are the weak point in these magazines not the springs.

Oh, by the way, forget about downloading your magazines to 28/18 rounds. Murphy Research Next Generation magazine springs will feed 30/20 rounds all day long without a belch.

This is just perpetuating an AR15/M16 myth. The magazines always functioned loaded to full capacity. The practice of downloading them was started to keep soldiers and Marines from overloading them. They will take 21 and 31 rounds respectively, but will not function loaded that way. When the M16 first hit the field ammunition was often issued in 20 round cardboard boxes and not on stripper clips. It was easy for the soldier to put more then 20 rounds into the magazine and set up a malfunction. The load 18 was the command's way of making sure that didn't happen. Once ammo became available on stripper clips, many units discontinued the practice of downloading magazines. Many currently active trainers advocate downloading your magazines, but to make them easier to seat on a closed bolt, not because they are unreliable fully loaded. In fact one of the benefits of the new HK steel magazine is that it's a little longer allowing you to easily insert the magazine with the bolt closed when it's fully loaded.

I think I'm going to continue to use my USGI magazines and take the money I could spend on retrofitting the springs and buy more ammo to practice with.

Jeff

[Sven]

A gunsmith I know says these are the best springs you can get, and they last longer. Thing is, many gunspring companies who use good old fashioned wire don't want you to know that because:

a) they don't produce them, and
b) they require less frequent updates

That said, some people swear by the standard springs and I can't argue with them.

[twoblink]

I think it's suppose to keep it's "spring memory" a lot better. (your k, in kx if you remember your physics)

That said, If Skunky says they are tactical, then I will consider them, otherwise, nope.

[mete]

OK ,then its "tactical " BS.

[WonderNine]

Any spring only has so many compressions and contractions in it before it wears out.

Yes, but are you saying spring steel and chrome silicon wire are the same thing? Sure doesn't appear so to me.

Yea, followers and feed lips wear out, but if the spring is golden, then at least that's one less thing you have to worry about. And how does spring steel compare in temperature extremes like sub-zero weather?

[Jeff White]

I don't know enough about metalurgy to know if chrome silicon wire springs last longer then plain carbon steel springs. I do know that after almost 30 years experience with the M16 rifle, that the springs in the magazines have never been an issue. Feed lips, yes...springs no.

As for cold weather performance, the military tests all of it's equipment in every climatic extreme there is. If the current issue springs were not reliable after being cold soaked they would not have been purchased.

I'm not saying that chrome silicon wire springs aren't better then the standard springs. I'm wondering if they are enough of an improvement to justify the cost and time to change them out. The line about the magazines not being reliable fully loaded is the big clue that they are hyping things a bit. Because it's not true. I'm always suspicious of advertising that says the product solves a non-existant problem.

I know a lot of people who have spent a lot of money on green followers and Wolff springs to fix magazines that are functioning fine. Sure the new production magazines are coming out with green followers, but there has been no recall of the old ones. Why do you think that is? It's because the performance with the green followers is not improved enough to justify the cost.

If the new magazines are in fact being made with chrome silicon wire springs, that's one thing, but it's an issue like the green followers, is the improvment enough to justify the cost in changing over the existing ones? To me it's probably not.

Jeff

[mete]

Wondernine , if a steel is used for springs it is by definition a 'spring steel'. The 92xx steels have long been used for springs. And to repeat comments that I have made on other threads - springs , if heat treated properly DO NOT 'take a set '. This is one of the ever reappearing urban myths.

[Matthew_Q]

Has anyone tried the 'Titanium' springs that Olympic Arms offers?

[marvl]

So are there any commercial suppliers of csw mag springs for AR15s and 1911s?

[Sven]

Here you go, info and parts you can order, brought to you by the world champion:

http://www.zediker.com/tubb/images/speedlock/slsprings1.html
http://www.zediker.com/tubb/images/speedlock/slspringsar15.html
http://www.zediker.com/tubb/images/speedlock/slnmtriggerspgs.html

[tex_n_cal]

Let me comment that I work for _____Spring Co, have been there for nine years, and prior to that worked for ____ Spring Division of _____Corp for nine years. I don't sell gun springs, so you can assume that I don't have any axes to grind.

Chrome silicon in one variety or another is used in suspension springs, as well as engine valve springs. In both cases, we're using more and more 9258+V materials, which can be very hard, yet still tough.

Chrome silicon in one variety or another does have somewhat better long-term sag resistance than carbon steels, like music wire. 1000x better? No way.

My personal opinion is that so-called "rocket wire", or high-tensile music wire is really a better choice for gun springs, if it is processed correctly. There are lots of subtle tricks in making springs, and material choice is only one of them. In the small wire sizes used in recoil springs, rocket wire has higher tensile strength than chrome sil, based on a perusal of current SAE and ASTM specs for the wire. 17-7 is an excellent spring wire, too, if stainless is desired.

Titanium springs? BTDT. In a mainspring, they will theoretically release their energy faster, by a smidgeon, due to its higher energy storage per mass. Make a practical difference in a gun? Maybe if you're trying to get 5000 rpm, otherwise no. They really work better on larger springs, where weight, space, or corrosion is an issue.

One of these days I really need to start my own gunspring business:evil:

[Sven]

Let me know if you need investors.

[COOL]

USPSA and IDPA shooters have used http://www.ismi-gunsprings.com/navigation.html
for years.

[rsilvers]

BTW, it is marketing BS that CS springs are superior to stainless. Especially 17-7 stainless is great.

The advantage of CS over music wire is that they are 475 degree rated rather than 250. However, stainless is even higher temp and in some alloys with no loss of spring properties compared to CS.

[DBR]

It is also a magazine design issue. Many modern high cap magazines (esp pistol) exceed the normal engineering parameters for acceptable spring stress given the quality of the issued springs.

After market, better quality springs can sometimes help rectify this problem.

Conservative magazine design (under loading) is better.

[DBR]

Music wire springs, even good quality ones, are at the bottom of the food chain endurance wise. Why would anyone in the gun spring business make the "ultimate spring" that never has to be replaced? To stay in business they would have to charge so much no one would by their springs.

Some gun designs assume short spring life in their specs. The problem I have with this is if the weapon is intended for self defense the owner never knows where they are in the spring life/reliability cycle.

OEM manufacturers (usually) only want the least expensive option that will make their product reliable for the average user (who may hardly ever shoot the gun).

For things like 1911 recoil springs, AR15 ejector and extractor springs and "under designed" mag springs in Glocks, Berettas and many other hicaps, after market CS springs can be real benefit IMHO.

The alternative to high quality springs is very conservative design. For example AK47, SKS and other low end military designs. The price is lower capacity and usually heavier weapons.

[kilo729]

If I'm not mistaken these things rust faster than SS.

[Tinman357]

I have IMSI springs in the two guns I carry to defend my daughter and myself. Nuff said.. :neener:

[DBR]

In my experience CS is no more prone to rust than music wire. CS does sometimes have a coating of oxide from heat treating that looks like rust. If they are properly shot peened after heat treating they are dull black.

I wipe down all off my gun springs with a patch using Eezox. CLP works about as well. I have never had a mag spring (or any other spring) fail from rust. Have you?

For the anticipated non military uses I think there are benefits to CS springs. 17-7 alloy springs are also excellent but they are not generally available except for AR mags.

[rsilvers]

It does seem possible that some gun mag springs are designed outside the limit of spring technology. If I ever learn of such a gun I will never buy it.

I am going to analyze the 1911 spring and post a report.

[rsilvers]

Interesting. My initial analysis is that a 1911 spring in full recoil is over-stressed. I am getting 60% of tensile. A spring should not go over 45%. A 1911 spring at full recoil is 1.62 inches long and really it would be good to never let it go below 2.8 inches long.

[Justin]

This thread was started a few years ago. Usually the policy is to close threads that are pulled up from so long ago. However, in this case, the content is good enough that I'm not going to close this one.

[rsilvers]

Wolff Springs now has CS.

"While Chrome silicone is and excellent material, it is a softer material and does not offer the tensile strength of our proprietary HTCS spring material - the material most of our springs are produced from. We now offer these springs due to customer requests. "

I see they got tired of telling people CS was not the best material and figured it was easier to just sell it.

[DBR]

It isn't the tensile strength which is of concern in spring design. It is the "proportional limit" which is less than the yield strength of the material.
http://www.ae.msstate.edu/~masoud/Teaching/SA2/def.proportional_limit.html

There is another issue with recoil springs. Even if the spring is OK at full design static compression, unless it is not over stressed at "coil bind" the compression wave that runs down the spring during dynamic recoil may over stress it.

Because of the very low cycles a mag spring sees it can be designed closer to the proportional limit than normal spring design criteria. Never the less many mag springs are still overstressed.

[DBR]

Not to nit pic: but the material is "chrome silicon". "Silicone" is usually an elastomer.

[rsilvers]

Yes but that is the same as what I said because the amount of stress where the strain gets out of proportion occurs at 45% of the minimum tensile strength of chrome silicon, 17-7, and music wire. So in effect, all that matters is minimum tensile strength of each of those materials.

For music wire, it is 230-399 KSI. For chrome silicon, it is 235-300 KSI. For 17-7, it is 235-335 KSI.

From this data, one can see that there are types of music wire which have higher tensile strength properties than the best chrome silicon. And since the 45% ratio applies for both, then music wire can be LESS likely to take a set than CS.

For a recoil spring, is a marketing trick that seems to have worked. For higher temp apps, that is another matter.

http://www.tribology-abc.com/calculators/properties_of_common_spring_materials.pdf

[rsilvers]

That was just a quote from Wolff's web page.

[rsilvers]

I would love if someone would compile a list of semi auto pistols who's factory magazines, when fully loaded, had a ratio of stress to min tensile strength of more than 45%. We might learn that such-and-such's 12-round .45 is really an 11 round .45. This would be one more tool to help decide on a platform.

[DBR]

There is another interesting thing I've noticed re music wire. If I try to bend an ISMI CS spring is takes quite a bit of force but when it does bend (take a set) it does it "all of a sudden" like the wire got soft. If I do the same thing with a Wolff music wire spring it resists all the way.

It seems the ISMI CS spring material has quite a dip after the yield point is reached. Does it matter? I don't know. The only feeling it leaves me with is a CS spring might be more likely to break compared to a music wire spring which just seems to weaken.

There are other relevant material issues such as fatigue resistance and "toughness". I don't know where the two materials score here.

[DBR]

There is another difference between music wire and other springs. As far as I know music wire is wound cold with no further processing. Most CS springs are wound then heat treated and stress relieved. To fully understand the stress situation with a music wire spring it seems some allowance needs to be made for the residual stresses in the wire after winding.

Maybe I'm over thinking this but there has to be some reason why a Wolff 1911 recoil spring is getting tired after 3000 rounds and an ISMI spring shows no change.

I think it probably relates to the fatigue resistance of the material.

[rsilvers]

Cold wound springs always need to be stress relieved -- that is how they become at rest with their new shape. It is hot-wound which do not.

I believe there is a big fatigue issue with 1911 recoil springs. Every time I plugged the USGI 1911 spring into a spring calculator, it warned me about fatigue for that design.

Per dwg 5013200 Rock Island Arsenal, Dept of the Army, 1 May 1928:
d = .043, OD = .430, free length = 6.55, active coils = 29, total coils = 30
8.00# @length of 3.72"
3.55# @length of 1.81"
2.88 #/inch
solid length = 1.375
music wire, QQ-W-470
Stress relieve 20 minutes @450F after forming

Does the Woff and ISMI have the same number of coils and the same wire diameter?

[rsilvers]

http://www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?p=0&t=1&i=603

"Chrome Silicon springs can withstand temperatures of 1300 degrees maximum. This is far more than what is required in most firearms."

This is not true. They are only rated to 475 degrees. If you want to go higher, there is stainless steel.

http://www.mwspring.com/materials.html

I suspect the set can be explained more by the heat-treat or stress relieving of the material than by the alloy itself.

Also I did not see the wire diameter in the test. Was it the same for each alloy?

[rsilvers]

http://books.google.com/books?id=08FkBSjG2bMC&pg=PA301&lpg=PA301&dq=fatigue+resistance+chrome+silicon+spring+music+wire&source=bl&ots=M9KucTZEvv&sig=E5BdQ3FTQP-VFDeMWI7bNWJGl6o&hl=en&ei=_8bzSf7QOJauMfa6nc8P&sa=X&oi=book_result&ct=result&resnum=9#PPA300,M1

Music Wire:
Due to superior surface quality, these can withstand higher stresses under repeated loading than any other spring material.

http://www.centuryspring.com/pdfs/techfaqs.pdf

"14. What are the best materials for fatigue applications?

The two most popular materials for fatigue
applications today are Music Wire (ASTM A228) and
Chrome-Silicon Valve Spring Quality (ASTM A877).
At wire sizes below approximately 0.080" (2.0 mm),
Music Wire offers higher tensile strength; however,
Music Wire’s maximum service temperature is less
than that of Chrome-Silicon."

Since a 1911 spring is 0.043 wire, and since it is an application below 250 degrees F, music wire is best. Chrome Silicon is speced for engines only due to the high temp environment.

[rsilvers]

Both hard drawn wire and music wire gain their
strength through cold drawing the wire from large
diameter rod to its final size. There are three
significant differences. First is the chemical
composition of the wire. Music wire contains more
carbon and less manganese than hard drawn wire.
Additionally, the allowed levels of contaminants such
as phosphorus and sulfur in music wire are more
restrictive. The second key difference is in the wire’s
strength. Because of the additional carbon, music
wire can be drawn to significantly higher tensile
strengths than hard drawn wire. Finally, processing of
music wire is done in a manner to provide a finished
surface with smaller allowed defects than hard drawn
wire. Since surface defects are one of the most
common initiation sites for fatigue cracks in springs,
smaller surface defects (and their corresponding
reduction in stress concentration) enable music wire
to be used in high cycle fatigue applications. Hard
drawn wire is best suited to static or very low cycle
service conditions.

[DBR]

What Wolff has sold as a "standard" 1911 recoil spring is .0445 wire with 32 coils. The end coil on one end is closed so call it 31 coils. On my spring tester it shows 8-8.5# at in battery length and 17# +- at full recoil length. This is a spring with about 500 rds on it.

The 18# Wolff springs I have are 31 1/2 coils for .045 wire. Again with a closed coil on one end. They test 9# in battery and 18#+- at full recoil

ISMI seems to use .044 wire and 32 coils for the "16#" spring and 30 coils for the "18#" spring. The free length of the ISMI spring is longer and it stays longer than the Wolff by about 1/2" after several hundred rounds. The ISMI springs are about 9# in battery and between 16 and 17# at full recoil. They also have a closed coil on one end.

This info is from memory. I think it is accurate. All of these springs were purchased at least five years ago.

[rsilvers]

The reason why this spring stuff is so interesting to me is that from when I first got into guns until just a few years ago, I bought all of this aftermarket 'upgrade' stuff hook-line-and sinker. I thought I needed to remove my brand new factory springs and barrels and replace them with aftermarket parts. Now I only replace things when testing shows an advantage and I am all about factory barrels and original parts now.

I am simulating both the Wolff and ISMI 16# spring specs you listed and doing it with them both the same material to see how just the spring form differs.

The Wolff is giving 70% of tensile when compressed to 1.62 inches. Load says 16.0 lbs. Stress is 178176. This is if it is 31 total coils and 1 dead coil.

ISMI. I cannot be sure if you are saying it has the same number of coils as the Wolff but I think you are. So all I am doing is changing the wire diameter and adding 1/2 inch of length. Stress goes up to 191757 which is 75% of tensile. Load is 16.6#

Now if you meant to say the ISMI has one more coil than the Wolff, then it is 16.1# load and 185571 stress and that is 73% of tensile. This seems more likely.

I would say if one is doing better than the other it likely has to do with heat-treat and stress relieving. Maybe ISMI just did a better job of that part. Or maybe their shot peening made the difference.

[DBR]

Sorry for the confusion. The ISMI 16# has 32 coils with a closed coil on one end so call it 31 active coils - same as the Wolff but it is .044 wire and has a 1/2" longer free length.

The 18# ISMI has 30 coils of .044 wire with a closed coil on one end so call it 29 active coils and it is also 1/2" longer than the Wolff free length.

Free length is after initial set.

Your calculations are in pretty good agreement with my spring tester which is probably only accurate to +-1/2# at best.

What seems to happen is the music wire springs gradually get shorter over time and after an initial set the ISMI springs do not. If the music wire is near the low end of expected tensile strength and the CS wire is at the high end that might account for the difference.

Both Wolff and ISMI claim to use certified material but who knows what the cert is.

[DBR]

On a different note, one reason I have been using the ISMI springs in my 1911s is they seem to be more consistent over time (cycles). To me that is a good thing.

On the other hand I use Wolff mag springs in 1911s and Glocks and have mags that have been loaded since 1994 and emptied once or twice a year and they are fine. I can't say that for the factory mag springs (Glock, Wilson, Metalform, McCormick etc).

[rsilvers]

Can you build a cycle machine that uses an electric motor to spin a wheel and convert that to linear motion and cycle the springs to 1.625 inches 100,000 times each? You can measure every brand standard spring before and after the test for load (not sure length matters -- only load at operating length).

Whatever the outcome, I would attribute it to the tensile strength on the cert, the spring form, and the heat-treat / stress relieve more than the alloy. But at least everyone would know what spring to buy.

[DBR]

At least based on that particular batch of springs.

Color me a skeptic when it comes to consistency although I have to say Wolff and ISMI seem to be pretty good.

[DBR]

As to your question regarding the testing machine, yes I can build such a machine and conduct the tests if someone wants to pay for it.

[HeavenlySword]

lols, contact the box of truth, the guys there will be glad to have something else to put up

[Ky Larry]

I have read on this, and other forums, about 1911 pistol magazines being left loaded for over 40 years and they function just fine. Do we have enough experience with these springs to positively prove they are an improvement? Just curious.

[rsilvers]

The myth of the chrome-silicon gun spring ‘not taking a set.’


It is NOT true that chrome silicon magazine springs are more resistant to taking a set than all stainless steel or music wire. I wish I could say that I am surprised this false marketing claim took hold, but sadly in the past I believed it as well. That is, until I researched it.

Springs have a characteristic called the proportional limit. When you compress a spring, you add stress. When the spring deforms, that is strain. Normally there is a proportional ratio between stress and strain. If you continue to deform the spring past a certain point, this ratio is no longer proportional and you have reached the limit for taking a permanent deformation (set). For three types of springs commonly used in guns, Music Wire (ASTM A228), Chrome-Silicon Valve Spring Quality (ASTM A877), and 17-7 PH stainless - the stress limit is 45% of the minimum tensile strength on the material certification.

For music wire, the range of the tensile strength property is 230-399 KSI. For chrome silicon, it is 235-300 KSI. For 17-7 PH, it is 235-335 KSI.

http://www.tribology-abc.com/calculators/properties_of_common_spring_materials.pdf

One cannot make a general statement about any of these materials without knowing the exact tensile strength of the specific material the spring maker used. You can see they have overlapping strengths, so without further information, they can be considered about the same.

One brand may make a better choice on post-winding stress relieving, or some post-processing such as shot peening, but one thing is clear – the BEST music wire is stronger than the BEST chrome-silicon. This is because with the higher tensile strength, 45% of that will be a higher stress value that one can impart before there is disproportionate strain resulting in a permanent set. Music wire wins the ‘resistance from set’ argument.

So why does chrome silicon exist? Music wire is limited to 250 degrees F. In a car engine, the temperature exceeds that. Chrome silicon wire is used for valve springs for this reason. It is more resistant to taking a set AT TEMPS ABOVE 250 degrees. Needless to say, firearm magazine springs do not reach this temperature and recoil springs likely never will either (AR extractor springs may). And if you want to go above the 475 degree F limit of chrome silicon, there are stainless alloys. They cost more, but have similarly high proportional limits as chrome silicon.

There is also an issue of fatigue strength. This is the ability to resist damage that occurs from cycle loading. Cycles are often measured in thousands or millions, and are not that important for magazine springs. They are important for recoil springs. Does chrome silicon wire outperform music wire for fatigue strength? No, it is worse. Music wire has a cleaner surface – and surface defects can reduce fatigue strength.

http://tinyurl.com/c9hdqu

“Music Wire:
Due to superior surface quality, these can withstand higher stresses under repeated loading than any other spring material.”

http://www.centuryspring.com/pdfs/techfaqs.pdf

“14. What are the best materials for fatigue applications?

The two most popular materials for fatigue applications today are Music Wire (ASTM A228) and Chrome-Silicon Valve Spring Quality (ASTM A877). At wire sizes below approximately 0.080" (2.0 mm), Music Wire offers higher tensile strength; however, Music Wire’s maximum service temperature is less than that of Chrome-Silicon.

… processing of music wire is done in a manner to provide a finished surface with smaller allowed defects than hard drawn wire. Since surface defects are one of the most common initiation sites for fatigue cracks in springs, smaller surface defects (and their corresponding reduction in stress concentration) enable music wire to be used in high cycle fatigue applications.”

The way one designs a spring to not take a set is to physically not allow it to deform in a way where the stress exceeds the proportional limit. This may mean designing a pistol magazine to only take 12 rounds rather than 13, or add more coils to the spring, or use thicker wire, or use flat wire, or increase the OD. A properly designed system will allow for a fully loaded magazine to sit for over 100 years, or for an action to remain locked open without the recoil spring taking a set. Are some platform magazines improperly designed? Most certainly, but no one has seems to identify which ones.

What about tests that prove chrome silicon gun springs take less of a set than music wire or stainless steel? I have seen a few tests and they prove no such thing. They are often done with different wire diameters, free lengths, number of coils, shot peening, stress relieving, and heat treatment. It is impossible to know if each spring was properly made. One does not need to do a test to know which alloy has a higher proportional limit as that is well known and defined in engineering texts. However, one can do tests to show if a specific brand spring is better than another specific brand spring but it would NOT be just because they replaced stainless or music wire with chrome silicon. So search for a quality spring, but don’t go by alloy alone.

So what is the ultimate magazine-spring material? Since all three have similar resistance to taking a set given the same wireform, one needs to look at cost, corrosion resistance, and temperature resistance. Temp resistance is not a factor and fatigue life is usually not either. Corrosion resistance is a strong factor. Cost is a factor for large production but not individual enthusiasts. 17-7 PH seems to win.

What is the ultimate recoil spring? Again all three have three have similar resistance to taking a set given the same wireform, In some applications, the 250 degree F limit of music wire is not an issue (handguns). In some (belt feds), it may be. If a pistol design allows for enough room to have a wireform where the ratio of stress to tensile strength stays low, then one may go with 17-4 PH to pick up corrosion resistance. If the design, as is true with a 1911, is one of high stress and yet temp is not a factor, then music wire seems to be best (I believe this is what Wolff uses). If the application is such where temps may get over 250 degrees F (either through combustion or simply through spring cycling) and there are high stress and fatigue considerations, such as an AR15 extractor spring, then chrome silicon would seem best. And if the temp gets really hot, such as in a gas block part, then 17-7 would be good.

For any spring, proper heat treat / stress relief and shot peening will increase the limits.

When you see a gun spring company claim chrome silicon is 1000 times more resistant to taking a set than music wire or stainless (yes I have seen this claim), you should ask them to prove it. They can’t, because it is not true. No non-gun based spring company seems to make that claim.

[rsilvers]

Statement: http://www.ismi-gunsprings.com/

"Because of the properties of music wire; it cannot be heat treated, shot peened and stress relieved after the spring is wound."

Reality:

Music wire gets it strength from being cold worked and does not require heat-treat after forming. It must be stress relieved. One does not shot-peen music wire because it already has a perfect surface finish from the cold-drawing process.

"Per dwg 5013200 Rock Island Arsenal, Dept of the Army, 1 May 1928:
d = .043, OD = .430, free length = 6.55, active coils = 29, total coils = 30
8.00# @length of 3.72"
3.55# @length of 1.81"
2.88 #/inch
solid length = 1.375
music wire, qq-W-470
Stress relieve 20 minutes @450F after forming"


http://home.earthlink.net/~bazillion/finish.html

"Spring wire that gets bent has to have the bending stress relieved. Here are the stress relief guidelines for all common spring wire materials. Music wire, 500 degrees F for one hour"

[tex_n_cal]

interesting thread...it appears to have risen from the ashes :)

I have noticed the Wolff spring take a set on first cycling, which tells me they aren't preset. rsilvers' Calculations agree with that scenario, as the stress at 60% will mean taking a set when it is first compressed to solid.

Presetting is commonly done on large suspension springs, where they are run long and pressed solid, or at least past the maximum deflection in service. It effectively increases the load carrying ability of a spring, leaving in place a beneficial residual stess. Perhaps ISMI is doing that process, so they don't settle on the first cycle, like the Wolffs. It is somewhat rare for small springs to get preset, as the process adds a fair amount of cost, percentage-wise to the spring.

ISMI claiming that music wire cannot be shot peened or stess relieved is just plain silly:neener:

Up above someone touched on the "compression wave". Some of the textbooks make reference to impact loading of a spring increasing stresses beyond what is calculated by static deflection. Perhaps that is why recoil springs can get tired over time.

Sometime back I ran across the exact dimension for the full compression of a 1911 recoil spring. Anyone have reference to that dimension? I am still half thinking I should start a gunspring company :evil:

[rsilvers]

1.62 inches at full recoil.

The preset theory is interesting. What is funny is when people do their experiments to prove CS will take less of a set and fail to consider that they may just be stressed at rest. This would be related to a post op and not the alloy.

[rsilvers]

Fundamentals of Spring Design from the Spring Manufacture's Institute, page 13, table SM-8 -- 17-7 PH stainless steel costs 2.75 times as much as Chrome Silicon valve-grade ASTM A401 in mill quantities.