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Possibly OT, but thinking about magazine springs taking a set

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  • johansen
    replied
    The manufacturer of a certain lamp socket (similar to mr-11/16, bi pin halogen lamps socket) told me that their 17-4 springs, upon lamp insertion, exert about 10 pounds of force on the lamp pin.

    at temperatures of 200-300C (normal operating temperatures) over the course of several hundred hours the pressure will decrease to about half, and remain at that level.

    the springs are relatively small, 3/16" long, maybe 1/8" diameter, probably 5 turns of .020" wire, when you insert the lamp the spring is just about fully compressed.

    anyhow, that was news to me that stress relief/creep would occur at that low a temperature.


    so i don't disbelieve some of you about springs taking a set, but.. some people have driven 500,000 miles on one set of engine valve springs.

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  • Sun God
    replied
    It's a function of stress in the material being loaded - the higher the stress, the lower the number of cycles before failure.

    This is usually illustrated using an S-N curve.

    Most plots imply graphically that below a certain stress threshold, the fatigue life of a part is infinite; however the current thinking is that while fatigue life in low stress applications is very large, it is not infinite - in the range of 10^7 (where many S-N plots end) to 10^10 cycles.

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  • wdtom44
    replied
    No doubt cycling a spring will fatigue it, but how many cycles does it take? Think valve springs engines, must be many millions or even billions of cycles. might be fun to figure this one out.

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  • 38_Cal
    replied
    My US 1841 Mississippi Rifle, made in 1850, has it's original springs and they're still plenty stout. The SMLE I had that was dated 1907 is still going strong for it's present owner, and it's all original. I've seen flat springs break as well as coil springs take a set, but there was always some outside factor such as poor heat treatment or a nick on the edge of a flat spring that led to the failure.

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  • wierdscience
    replied
    Awhile back I found a Ruger MkII mag that went missing 10 years ago.It was still loaded,so I emptied it,had no feed issues at all.

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  • oldwing
    replied
    Originally posted by Paul Alciatore View Post
    Well, the pistols used for boot camp training probably get a lot of use. And there is little call for more rounds in the magazine on the firing range. So, they may have been trying to keep the springs from fatigue.

    OTOH, I served in Vietnam and, on occasions, carried a 1911. When I did, it was ALWAYS loaded with a full clip and I had two or more additional full clips on me whenever I left the base camp. I was in the Ordinance Corps and never heard any admonition against a full clip in combat situations or others for that matter.

    Many times on the rifle and pistol ranges we were instructed to load only the number of cartridges that we were going to fire in a particular round. I think this was more of a safety precaution than anything else.
    I agree. I recall on the rifle range a couple times when there were problems on the firing line, and I was pretty glad those guys didn't have a few more rounds. I was in the Marines and I knew a guy who repeated the same nonsense I was taught, and he was an Army MP.

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  • Paul Alciatore
    replied
    Well, the pistols used for boot camp training probably get a lot of use. And there is little call for more rounds in the magazine on the firing range. So, they may have been trying to keep the springs from fatigue.

    OTOH, I served in Vietnam and, on occasions, carried a 1911. When I did, it was ALWAYS loaded with a full clip and I had two or more additional full clips on me whenever I left the base camp. I was in the Ordinance Corps and never heard any admonition against a full clip in combat situations or others for that matter.

    Many times on the rifle and pistol ranges we were instructed to load only the number of cartridges that we were going to fire in a particular round. I think this was more of a safety precaution than anything else.



    Originally posted by oldwing View Post
    I can't see any reason why they would take a set, but when I was in both boot camp and ITR, the DIs kept hammering home that a 1911 should be loaded with only 5 rounds in the mag. But then that was 48 years ago.

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  • Catshooter
    replied
    It's a well known and applied fact to many people that read the Glocktalk forum that leaving a brand new Glock mag loaded for a few months will make it easier to load. I've done it myself. So, at least some springs are affected a bit by leaving them compressed for a time. It can make the difference for some between being able to load the mag by hand or having to use a loader. The mags still function perfectly.


    Cat

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  • ikdor
    replied
    So, does this mean that you don't need to turn your torque wrench to a low value after use? Same fairy tale.

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  • oldwing
    replied
    Originally posted by Doc Nickel View Post
    -I suspect that was a lot closer to the same reason Andy only gave Barney one bullet, than having anything to do with the springs.

    Doc.
    Well, the DIs weren't trying to encourage us to think for ourselves. They were more interested in teaching us what to think.

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  • flylo
    replied
    I left some loaded for years with no problem.

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  • Doc Nickel
    replied
    Originally posted by oldwing View Post
    I can't see any reason why they would take a set, but when I was in both boot camp and ITR, the DIs kept hammering home that a 1911 should be loaded with only 5 rounds in the mag. But then that was 48 years ago.
    -I suspect that was a lot closer to the same reason Andy only gave Barney one bullet, than having anything to do with the springs.

    Doc.

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  • BCRider
    replied
    Some cheaply made springs will "take a set". But that's only because they are cheaply made and shortcuts were done during the making of them. As mentioned frequently a good spring should not collapse from being compressed up to it's maximum intended compression.

    I suspect it's the cheaply made craptastic spring products that gave rise to the idea that springs left compressed over time will "take a set".

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  • ncjeeper
    replied
    Originally posted by KJ1I View Post
    We escaped from California in 1994.
    Good for you.

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  • oldwing
    replied
    I can't see any reason why they would take a set, but when I was in both boot camp and ITR, the DIs kept hammering home that a 1911 should be loaded with only 5 rounds in the mag. But then that was 48 years ago.

    Leave a comment:

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