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Thread: Loaded Magazine Confusion

  1. #21
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    Quote Originally Posted by Jstud220 View Post
    Gen 2 pmags also work just fine stored with 30 rounds
    Was not my intention to start that debate.
    It's hard to be a ACLU hating, philosophically Libertarian, socially liberal, fiscally conservative, scientifically grounded, agnostic, porn admiring gun owner who believes in self determination.

    Chuck, we miss ya man.

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  2. #22
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    Quote Originally Posted by lfdtom View Post
    But but but your feedlips will spread. All joking aside I’ve never had issues with Gen 2 or 3 PMAGS loaded for years.
    Honestly, I've got some late 1970s USGI mags that are still running without issue, without a single failure and they are on their original springs even. They only thing I've ever replaced is the black original followers for the green "no tilt" followers sometime mid 1990s. Round counts have to be something like 5,000 at this point. I think I got my SP1 carbine around 1982 and snapped up a could dozen surplus USGI mags (Adventure, Center, Okay and some factory Colts). I even have some aluminum follower 20 rounders (I think 72 date) that are still running without issue but don't have the same round count as my 30s.
    It's hard to be a ACLU hating, philosophically Libertarian, socially liberal, fiscally conservative, scientifically grounded, agnostic, porn admiring gun owner who believes in self determination.

    Chuck, we miss ya man.

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  3. #23
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    It’s strange that people tell you that a spring under static compression doesn’t weaken, but then elsewhere advocate leaving a magazine loaded or a slide locked back to rectify an overly stiff spring. HK and Wolff Gunsprings believe a spring compressed does weaken.

  4. #24
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    Quote Originally Posted by ViperTwoSix View Post
    2. It has been proven that spring life is affected by spring compression cycles, not time under tension.
    Not quite.

    "EVALUATION OF PRETREATMENT PROCESSES AND LONG-TERM STORAGE ON MAGAZINE SPRING FOR THE M14, 7.62MM, RIFLE," LaRiviere, Feb 1966, Springfield Armory, MA

    "PERFORMANCE OF 5.56-MM 30 ROUND MAGAZINES AFTER EXTENDED LOADED STORAGE," Foltz, Grego, Escalona and Ritschel, ARDEC, Picatinny Arsenal NJ

    The purpose of this test was to determine if storing of a loaded 5.56-mm, 30 round tan follower magazine [part number (P/N) 13021312] with M855 ball ammunition for an extended period of up to 5 yr would degrade the magazine spring to the point that its spring force would not properly load ammunition into the host weapons: the M4A1 and M16A4. It is important that the magazine spring supply enough force to chamber the next cartridge properly, otherwise the weapon may misfire (ref. 1). . .

    Beginning in April 2011, three hundred 5.56-mm, 30 round magazines were loaded with M855 ammunition. Prior to loading, each magazine’s spring force was measured in accordance with (IAW) DR 13021312, note 2, which allows the spring force when depressed 0.25 in. to be between 2.5 and 3.5 lb. Once loaded, all 300 magazines were placed in a storage bunker located at the U.S. Army Armament Research, Development and Engineering Center, Picatinny Arsenal, NJ. In 6 month intervals, over the 5-yr period, 30 magazines were removed from storage and fired, 15 on an M4A1 and 15 on an M16A4. The cyclic rate of the weapon was recorded as well as the spring force of the magazine when empty.

    In a previous evaluation of long term storage conducted on M14 magazine springs, it was shown that the majority of spring force degradation due to extended storage occurs in the first two years, as shown in figure 1. Therefore, it is probable that if the 5.56-mm, 30 round magazines still fire properly after 2 yr of storage, then longer intervals of storage would not cause system failure since the majority of spring set would have already occurred (ref. 4).



    There is a loss of spring load due to extended compression.

    HOWEVER:

    The minimum spring strength specified on the drawing IS NOT the the minimum strength required for reliable operation. Magazine springs can be considerably softer than the print minimum and still work fine. Think about it, they have to be otherwise many springs wouldn't work correctly right out of the box.

    Also note the curves flatten out after the first two years, so it is only after two years that continuous compression that there is no further degradation of spring strength.

    So, the next question: How many cycles to wear out a spring?

    Well, the M14 test is try and answer this and configure a machine to compress about 20 M14 magazine springs from empty length to full magazine length. After 10,000 cycles the springs lost just over 3/4 pound of strength. Since the M16 magazine spring is a different material, there might be some differences in spring life.
    Last edited by lysander; 07-02-22 at 08:29.

  5. #25
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    Quote Originally Posted by Harpoon View Post
    It's Hooke's Law. You can look it up. It basically says that keeping a loaded mag is ok on the springs.
    That's not what Hooke's law states.

    Hooke assumed a perfectly elastic material, steel is not perfectly elastic.

  6. #26
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    Quote Originally Posted by lysander View Post
    HOWEVER:

    The minimum spring strength specified on the drawing IS NOT the the minimum strength required for reliable operation. Magazine springs can be considerably softer than the print minimum and still work fine. Think about it, they have to be otherwise many springs wouldn't work correctly right out of the box.

    Also note the curves flatten out after the first two years, so it is only after two years that continuous compression that there is no further degradation of spring strength.

    So, the next question: How many cycles to wear out a spring?

    Well, the M14 test is try and answer this and configure a machine to compress about 20 M14 magazine springs from empty length to full magazine length. After 10,000 cycles the springs lost just over 3/4 pound of strength. Since the M16 magazine spring is a different material, there might be some differences in spring life.
    Excellent post, thank you.

    Somewhere around here is a similar post discussing an (initial-set? first-set?) springs experience resulting in a loss of force/strength at that time. It wasn't meaningful but it did occur. One of the engineer-types was involved, maybe you participated too.

    I've found mags in nooks and crannies that were years lost. They generally worked, those that didn't had some sort of debris inside them or physical damage.
    2012 National Zumba Endurance Champion
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  7. #27
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    Quote Originally Posted by lysander View Post
    Not quite.

    "EVALUATION OF PRETREATMENT PROCESSES AND LONG-TERM STORAGE ON MAGAZINE SPRING FOR THE M14, 7.62MM, RIFLE," LaRiviere, Feb 1966, Springfield Armory, MA

    "PERFORMANCE OF 5.56-MM 30 ROUND MAGAZINES AFTER EXTENDED LOADED STORAGE," Foltz, Grego, Escalona and Ritschel, ARDEC, Picatinny Arsenal NJ

    The purpose of this test was to determine if storing of a loaded 5.56-mm, 30 round tan follower magazine [part number (P/N) 13021312] with M855 ball ammunition for an extended period of up to 5 yr would degrade the magazine spring to the point that its spring force would not properly load ammunition into the host weapons: the M4A1 and M16A4. It is important that the magazine spring supply enough force to chamber the next cartridge properly, otherwise the weapon may misfire (ref. 1). . .

    Beginning in April 2011, three hundred 5.56-mm, 30 round magazines were loaded with M855 ammunition. Prior to loading, each magazine’s spring force was measured in accordance with (IAW) DR 13021312, note 2, which allows the spring force when depressed 0.25 in. to be between 2.5 and 3.5 lb. Once loaded, all 300 magazines were placed in a storage bunker located at the U.S. Army Armament Research, Development and Engineering Center, Picatinny Arsenal, NJ. In 6 month intervals, over the 5-yr period, 30 magazines were removed from storage and fired, 15 on an M4A1 and 15 on an M16A4. The cyclic rate of the weapon was recorded as well as the spring force of the magazine when empty.

    In a previous evaluation of long term storage conducted on M14 magazine springs, it was shown that the majority of spring force degradation due to extended storage occurs in the first two years, as shown in figure 1. Therefore, it is probable that if the 5.56-mm, 30 round magazines still fire properly after 2 yr of storage, then longer intervals of storage would not cause system failure since the majority of spring set would have already occurred (ref. 4).



    There is a loss of spring load due to extended compression.

    HOWEVER:

    The minimum spring strength specified on the drawing IS NOT the the minimum strength required for reliable operation. Magazine springs can be considerably softer than the print minimum and still work fine. Think about it, they have to be otherwise many springs wouldn't work correctly right out of the box.

    Also note the curves flatten out after the first two years, so it is only after two years that continuous compression that there is no further degradation of spring strength.

    So, the next question: How many cycles to wear out a spring?

    Well, the M14 test is try and answer this and configure a machine to compress about 20 M14 magazine springs from empty length to full magazine length. After 10,000 cycles the springs lost just over 3/4 pound of strength. Since the M16 magazine spring is a different material, there might be some differences in spring life.
    Was there a control group?
    Im curious what the results would be from unloaded mags.

  8. #28
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    Quote Originally Posted by Uncas47 View Post
    No worries, just pick a side and dig in.
    Truth.

  9. #29
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    Quote Originally Posted by 1168 View Post
    The spring wearing out “problem” is simply bunk. I’ve used mags that I loaded in the previous deployment, on my next deployment. As to trouble seating a full mag on a closed bolt, the Gen 3 PMag was purposely designed to almost hold an extra round for that purpose. USMC issues them….
    The fact that MAGPUL designed the Gen3 PMAG with this feature validates the concept of downloading GI mags by 1 or 2 for seating mags on a closed bolt and not damaging the spring from over compression.
    America First

  10. #30
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    Quote Originally Posted by Alpha-17 View Post
    The military frequently get a lot wrong.
    It's all about greasing palms.

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