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.
Last edited by Chuck Haggard; 01-02-2015 at 01:10 PM.
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?Originally Posted by Jeep
--Josh
“Formerly we suffered from crimes; now we suffer from laws.” - Tacitus.
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.
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.
Last edited by David Armstrong; 12-30-2014 at 12:20 PM.
"PLAN FOR YOUR TRAINING TO BE A REFLECTION OF REAL LIFE INSTEAD OF HOPING THAT REAL LIFE WILL BE A REFLECTION OF YOUR TRAINING!"
I find it hard to wound up about coil springsI suppose I take their performance and low replacement cost for granted.
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?
Sure dude. Gimme a few minutes.
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.
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.
Think for yourself. Question authority.
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
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