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Old February 21, 2021, 11:49 AM   #1
Bart B.
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Firing Pin Spring Strength

Anyone ever compared a firing pin spring pounds rating to factory specs?

They weaken with age. That increases velocity spread and decreases average velocity

Last edited by Bart B.; February 21, 2021 at 11:56 AM.
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Old February 21, 2021, 12:21 PM   #2
Grant 14
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Be careful of firing pin springs bought off of the internet. I bought one advertised for my Savage 1899 and it was too long to even fit, let alone too strong. I ended up cutting it down a little at a time until it functioned properly. Grant.
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Old February 21, 2021, 02:47 PM   #3
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Why does everyone worry about springs?
They seldom, if ever wear out.
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Old February 21, 2021, 05:15 PM   #4
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They take a set over time. That can lead to less consistent ignition and greater velocity spread. That doesn't mean the guns stop firing, though, and certainly, in something like a pistol round at normal ranges, there's just no advantage to that last little bit of velocity consistency as the gun's inherent accuracy limits spread the groups more. It does matter to 1000-yard shooters, though. I believe Bart B. said he and the other Palma team shooters were replacing their springs every 6 or 7 years even if they'd just been sitting unused.
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Old February 21, 2021, 10:53 PM   #5
Bill DeShivs
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Springs take an initial set. After that, they have to be bent past their elastic limit to set any further. I have been working on guns for 50 years, and I have never replaced a spring unless it was rusted or overheated.
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Old February 22, 2021, 03:54 PM   #6
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Bill is correct.
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Old February 22, 2021, 06:09 PM   #7
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If you can shoot your stuff inside 6 inches at 1000 yards, you'll know when springs need replaced.
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Old February 22, 2021, 06:45 PM   #8
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So, if I don't shoot at 1,000 yards, I never need to replace springs???
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Old February 22, 2021, 06:49 PM   #9
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Quote:
Originally Posted by 44 AMP View Post
So, if I don't shoot at 1,000 yards, I never need to replace springs???
No, instead replace them when their cocked force is 5% below spec.
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Old February 22, 2021, 07:50 PM   #10
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How do you check the springs?
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Old February 22, 2021, 08:12 PM   #11
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I think part of what happens to a spring in a gun is that it gets used. The repeated flexing causes a bit of fatigue. Plus, the gun fires, which delivers a bit of a jolt to the gun. Blows do relieve stress, whether delivered by mechanical or magnetic means. So perhaps "taking" a set is too passive a description. It's more like imposed.
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Old February 22, 2021, 09:58 PM   #12
Bart B.
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Quote:
Originally Posted by chris downs View Post
How do you check the springs?
Compress it on a bathroom weight scale.

Have a gunsmith check it.
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Old February 23, 2021, 12:24 AM   #13
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Quote:
Originally Posted by Bill DeShivs View Post
Springs take an initial set. After that, they have to be bent past their elastic limit to set any further. I have been working on guns for 50 years, and I have never replaced a spring unless it was rusted or overheated.
Firing pin spring. Yep, same.

Shotgun mag tube springs wear out the fastest, but they are the weakest and abused the most. I've worn out mag springs and recoil springs, even a few striker springs, but never a bolt action firing pin spring.

I've checked mine on only one bolt action, about 9K rounds fired and 5k dry fires as of last year and still the same strength. But the rifle, with the original par load I have for it, shoots a good 80 fps faster today than it did 12 years ago when new. So maybe my firing pin spring is getting stronger.
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Old February 23, 2021, 11:50 AM   #14
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I have a number of Army shop manuals from the 70s. None of them use spring weight (strength) as the serviceability standard.

Spring length is the standard.
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Old February 23, 2021, 11:54 AM   #15
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Quote:
Originally Posted by 44 AMP View Post
I have a number of Army shop manuals from the 70s. None of them use spring weight (strength) as the serviceability standard.

Spring length is the standard.
Good idea.
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Old February 23, 2021, 12:57 PM   #16
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Board member Hummer70 said that when he was a test director at Aberdeen Proving Grounds, they used copper slugs in a fixture to test firing pin energy. The steel fixture was like a headspace gauge but with a primer pocket with a solid floor. A copper slug was set into the pocket and the fixture was chambered and the trigger pulled. The slug was indented by the firing pin (already checked for adequate protrusion) and the depth of the resulting indentation in the copper was measured to determine energy. I assume the slug maker had the equivalent of a copper crusher tarage table for the indentations for depth vs. firing pin energy.
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