Continuously Cocked Bolt and Spring Fatigue

[Glen]

For safety purposes, I see a lot of bolts open in rifles or completely removed from rifles when they are on display in stores. I always wonder if this is somehow fatiguing the spring or springs in the bolt and could cause malfunction?

 

[M-Cameron]

Nope, just Compressing a spring and leaving it does not wear it out....is the number of cycles a spring goes through that wear it out.

Similar to leaving a magazine fully loaded.

 

[PJSprog]

Yup, what M-Cameron said.

 

[Sunray]

Like M-Cameron says, springs do not lose temper from being compressed. Think in terms of your vehicle's springs. Those are under constant, long term, compression.
Even mag springs do not lose temper from constant use. The bends in 'em can get work hardened though. Being flat springs. Coil springs just keep going.

 

[jmr40]

Removing the bolt makes it useless for a thief. Leaving them open helps fit more on a shelf.

 

[Bart B.]

Why have all of my Win 70 factory coiled firing pin springs weakened from age and use?

Yes, I've measured them for force rating at compressed lengths when cocked. Spec'd at 23 pounds, they've weakened to 20 to 19 pounds after a few years. Yes, they still fired primers but not consistently. Caused elevation shot stringing at long range. I'm not the only person to observe this. I replaced them with Wolff 25 pound ones that last longer.

Seen the same issue with Garand hammer coiled springs when they got weak.

 

[tdstout]

Why have all of my Win 70 factory coiled firing pin springs weakened from age and use

You said it yourself, age and use. Not just being compressed and left alone.

I have had a fully loaded magazine sitting in a drawer for a couple of years that shot just fine when I finally tried it.

 

[Slamfire]

The CMP is out of Kimber M82G's, but the bolt on all of them had been taken out of the rifle and placed in the shipping container and left cocked for over 30 years. The Kimber has a marginal ignition system anyway and the mainsprings on most of these Kimbers have taken a set and give misfires. Particularly in cold weather.

I took the mainspring out and replaced with a new mainspring. There are enough shooters with the same problem that an aftermarket solution developed.

 

[ironworkerwill]

Steel springs will loose strength over time. It takes a very long time. Some springs are just better than others.

Think of automotive springs, it's the same thing. My Honda has been known for weakining springs and most other auto owners will never have a problem throughout the life of the vehicle.

 

[danez71]

Why have all of my Win 70 factory coiled firing pin springs weakened from age and use?

Yes, I've measured them for force rating at compressed lengths when cocked. Spec'd at 23 pounds, they've weakened to 20 to 19 pounds after a few years. Yes, they still fired primers but not consistently. Caused elevation shot stringing at long range. I'm not the only person to observe this. I replaced them with Wolff 25 pound ones that last longer.

Seen the same issue with Garand hammer coiled springs when they got weak.

That would be because despite what most are saying here, spring can and do loose some oomph from being compressed and left there and cycling is not not the sole factor of the wear.

If cycles was the sole factor of wear, people would be replacing recoil springs at least 10 to 1 to mag springs.... and that simply isn't the case.

I've gone around many times here with multiple engineers from different industries and at about the 3rd to 4th page they finally concede when they read all of the data I've supplied.

Search my screen name and elastic range to read hard evidence backed by scientific studies and data.


How much will it effect is far too complicated and we'll never have all of the details to figure out exact numbers.

 

[tuj]

I too had a CMP Kimber 82G that needed a new striker spring.

 

[BCRider]

Why have all of my Win 70 factory coiled firing pin springs weakened from age and use?

It is a poorly made spring in that case. It was not given the proper treatment after being wound.

It may sound odd but a well made spring will work harden over enough time and assuming it is used over enough of it's range of motion. That is why if used long enough they tend to snap or shatter at some point along their length.

The ones that collapse and get softer as a result are either using a poor quality steel in the first place or they are not correctly passivated after being wound.