A pic of the unusual follower (bottom), shown with a Pmag and USGI mag. I'm curious as to why the ARC feeds from the opposite side.
http://img.photobucket.com/albums/v5...n/IMG_6360.jpg
Printable View
A pic of the unusual follower (bottom), shown with a Pmag and USGI mag. I'm curious as to why the ARC feeds from the opposite side.
http://img.photobucket.com/albums/v5...n/IMG_6360.jpg
Ok, post your test data. Please specify the number of coils of each spring, the free length, the wire diameter, and the stress relieving and heat-treat process for each spring. Also the test procedure and results.
Here is one test where they 'proved it' but in fact they did not.
http://www.brownells.com/aspx/NS/Gun...?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?
Some gun spring makers have misrepresented the material. This is an anomaly in the gun works and you cannot get a real spring company or mechanical engineer to agree. Wolff finally gave in and stopped arguing with customers who were under the impression it was better, and now sells it. They have this on their website:
"While Chrome silicon 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. "
The advantage of chrome silicon over music wire is that it is 475 degree F rated rather than 250. However, stainless is even higher temp and in some alloys with no loss of spring properties compared to CS. CS is simply an intermediate step between music wire and stainless for temp resistance but does not have the corrosion resistance. When a spring corrodes, it loses its fatigue strength properties. This is because surface finish is very important. In fact one of the reasons why music wire has such excellent fatigue strength properties is because of the ability to put a good surface finish on it.
http://books.google.com/books?id=08F...um=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.
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.
The amount of stress where the strain gets out of proportion (and spring takes a set) 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 and 17-7 which have higher tensile strength properties than the best chrome silicon. And since the 45% ratio applies to all, then music wire or 17-7 can be LESS likely to take a set than CS. In reality, it depends on the specific cert of the alloy used and the post processing.
For a recoil or magazine spring, is a marketing trick that seems to have worked. For higher temp apps such as in engines, that is another matter.
http://www.tribology-abc.com/calcula..._materials.pdf
http://www.davidtubb.com/cs_springs.html
These may be quality springs with rigid QC and could be the best choice, but it is not because the material is better than music wire.Quote:
When a conventional spring is first installed is the last time it's doing its job as designed. Standard music wire springs are notorious for changing characteristics. We have all heard that a spring will take a "set" (compress to a shorter length) and then stay there for the remainder of its life. Not true! All springs continue to degrade and shorten with each cycle. The
You can design a spring to last for essentially unlimited cycles. It just becomes hard when you have a confined space it must work in.
question is when and how much? Our springs use the same Chrome Silicon alloy used in the manufacture of valve springs for Indy car engines. Those springs can easily endure over one million compression cycles at high temperature in one afternoon -- a much harsher
They can do a million cycles because they are designed with geometry to last that long. It has nothing to do with chrome silicon other than engines run at a higher temp than a gun so you cannot use music wire
environment than experienced in any firearm.
Oh, nothing so fancy. I'm not a test lab. I simply ran over a good number of springs with a semi and crushed a few more with a hydraulic press. The SS springs looked like spaghetti afterwards. The CS springs maintained their shape quite well.
http://azbattlerifles.com/images/DSC043422.JPG
I read that the TD mags have the "bump" on the follower on the left side so that when the bolt locks back on an empty mag, it's easier to see that the mag is empty.
Not sure if that is so, or not.
Interesting spring data guys.
I had not known that SS springs were of lesser performance/quality than the CS ones. Of course, all the hype is CS these days, as far as physical performance goes (without regards to rust/corrosion)
I've always wanted to just use SS springs in my mags, and never worry about corrosion. Maybe I'll try some out.
I would like to know if anyone has ever fully loaded a few mags with both types of springs, and let them set for years and years, and then maybe perform some testing afterwards.
Also, maybe some "cyclic" testing, with regards to compressing them repeatedly.... (CS vs SS)...
Does anyone here know what different options are available on the market, as far as 30rd USGI springs made of SS? Who all makes replacement springs in SS for 30rd mags?
I have never really thought about it, but are the USGI springs and PMAG springs interchangeable??? I know the followers are different, but what about the springs? Does a USGI spring work in a PMAG and vice-versa???
Thanks.
I will be stunned if someone can prove to me that the best chrome silicon is more resistant to taking a set than the best music wire at temps under 200 degrees F. STUNNED. It is impossible because it is not true. Music wire is higher performance than chrome silicon, except at high temps such as inside engines.
I started a thread on this:
https://www.m4carbine.net/showthread.php?t=30101