In the gun business braided springs are referred to as "nested springs" and they are really durable CIP AKs. The problems with most springs is they take a set or break.
The problem with springs is if not heat treated correctly they will take a set or break. Unless something has changed there is no way to test a spring except by compressing it a long period or it breaks as they are so small you can't ding it with a Rockwell checker. About all that can be done is check to see if it has enough energy as new with coppers and a bench inspection gage where the indent depth from the striker impacting the copper is measured in thousandths.
About the best an average user can do is restricted mostly to bolt rifles. You can get a new rifle, pull the bolt down, remove the striker spring, measure the free length with a caliper and record your reading. Then once a year pull it down and measure the free length again to see if it has become shorter.
On a real M16/M4 with burst control the striker spring on one side has less coils and as a result a few of the rifles that came in for M16A!E1 testing did not exhibit enough striker energy.
YOU CANNOT JUDGE STRIKER ENERGY BY LOOKING AT FIRED PRIMERS
Frankford Arsenal did a multimillion primer test and off set indents can cause them. By offset it is called "center fire ammo" right? The name of the game is for the striker to impact the center of the primer but when you are making thousands of rifles a week and you have folks that are making bolts that could care less because they are just there for a job. All they care about is getting paid.
One of the first things things my trainer impressed upon me was you can have a fine design but the "production floor" workers will take your marvel to it's knees. For instance I was given the "run" at a major vendor plant to just walk through the plant and observe all facets of production and I remembered my trainer so I stopped and talked to this guy who was making a part and asked him what the part did he was making and he had no clue.
A number of years ago the Shot Show was in Charlotte so my buddy and me went. I walked up to a vendor that I had just bought a rifle from and had checked the striker indent energy on and found it lacking so I walked up to this vendor area and asked if there was anyone there from engineering and they identified this one guy who proudly proclaims "I"M FROM ENGINEERING" and I asked him what the striker indent spec was and he did not have a clue of what I was talking about. He sent me to a technician from the plant who did not know either and told me immediately he did not but he was sure going to find out when he got back to work. Now that is an employee I would want.
I got home and wrote the company, told them what I had recorded in my testing and I got a email asking me to call their Public Relations manager as he and their chief engineer wanted to have a conference call with me and I learned that vendor had not checked striker energy on anything in over 15 years. They did not make their springs, they just ordered them in, put them in and shipped the rifles out.
There are several thing that will take your parade down quickly and a rifle going click instead of bang in a shootout is number 1 on the list. Clicks can be experienced from empty chambers (didn't feed correctly) FTC failure to close, FTL failure to lock, then you get a FTF. Such can be caused by mags. This is why in testing mags are numbered and at each failure everything shuts down while you figure out if you can thus the mag number is recorded and the round number in the mag is recorded and that mag is rotated through every other weapon to see if it repeats in that one, another one, or maybe two more. Then the paperwork is all changed blaming the failure on the magazine and not the weapon and the magazine is removed from the test and your very gently place it on a hard surface with surgical precision you take a hammer to it.
To be sure you can have the right spring, the correct energy and still get a failure to fire in cold weather due to your not using the correct lubricant for cold.
I am aware of one instance where a magazine caused multiple rifles to sustain catastrophic failures.
Had several of the coil springs in the 3 shot burst mechanism just break in my test.
Also had five (IIRC) failures to fire which really caused a stir. Five failures is allowed in 5 million rounds and I had that many in 244,000.
The normal human thought pattern seems to blame ammo for failures and yes this does happen but with new ammo right out of the cans the likelihood of it being just the ammo is somewhat reduced.
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Originally Posted by Humpy70
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