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Thread: Roles of Springs in the 1911

  1. #1
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    Wabash IN

    Roles of Springs in the 1911


    I wrote the below for a member of another board. It became longer and more in-depth than I'd originally intended and I'm posting it on several boards because I realized it might help others when it comes to gunsmithing their 1911 pistols.

    I'm not a 1911 expert. There are true 1911 artisans out there, and I don't belong to that society. Some do consider me an expert in the Mosin-Nagant, but I do not. I only study and report findings. A gun is a gun, but each has their own nuances which must be learned through intensive study, and a bolt action rifle is not a 1911. When I say "a gun is a gun" I only mean that they have the same basic parts, which may be extremely different.

    They have bolts or slides which feed the rounds and keep them chambered for firing.

    They all have hammers and firing pins (even if these are combined into single-piece units called "strikers".)

    They all have sears, and all have disconnectors after a fashion, even if the "disconnector" is a manual separation of the sear and hammer mating surfaces.

    All have springs, which are used to store energy for operation. In a manual pistol or bolt action rifle, this may only be the mainspring which drives the hammer. In a semi-auto, you may have three or more springs which all work together.

    Discounting the sear spring for now, in the 1911 pre-series 80, there are three basic springs which work in relationship during firing:

    1. The mainspring, which drives the hammer and retards the slide;

    2. The recoil return spring, which does act against recoil but is really made to return the slide after recoil;


    3. The firing pin spring, which returns the firing pin after ignition and prevents inertial firing.

    Let us for a moment consider only the mainspring. Imagine a 1911 with no return spring nor firing pin spring. Imagine a round chambered and full magazine loaded into this hypothetical pistol.

    When you squeeze the trigger, these events happen:

    1. The hammer drops, striking the firing pin.

    2. The round discharges.

    3. The slide and barrel assembly recoil as one piece, against the hammer.

    - This is important. This is the mainspring's role in managing recoil. The time the mainspring, through the hammer, can keep the barrel and slide locked together is called dwell time. Generally speaking, the more dwell time, the better. Early unlocking can cause a host of problems, from firing pin wipe to blowback of gasses during early unlocking.

    - Hypothetically, on a Government, the hammer and mainspring should provide all the control needed to retard unlocking of the slide/barrel assembly. This is theoretical and I wouldn't try it.

    - The original 1911 had a square-bottom firing pin stop. Because the military carried their pistols in Condition 3, and because some folks found it difficult to rack the slide with the hammer down in Condition 3 to ready their pistols, the 1911a1 was introduced as having a radiused FPS as one of its features. This allowed easier racking of the slide with the hammer down, but also hurt the dwell time. This wasn't important in a mass-produced fighting pistol, but most civilians ask more from their weapons and those who know change the stock radiused FPS to a square-bottom pre-a1 stop for better dwell time.

    - Take away from this that the primary recoil and barrel/slide lockup timing control is the mainspring, NOT the "recoil" (slide return) spring.

    Now, let's take up where we left off: The 1911 has recoiled against the force of the mainspring. The slide and barrel have successfully separated and now the slide is setting open after the extractor and ejector have worked their magic to discard the fired case.

    There is another round just begging to be fed if something would only move the slide forward to do it!

    Enter the recoil return spring.

    1. Upon ignition, the recoil spring begins compressing, storing energy released from the round.

    - The greater the amount of energy stored, the more force the recoil return spring will exert against the force of recoil. This means that the heavier the recoil return spring, the greater the feel of the recoil imparted to your hand.

    2. At full slide rearward travel, resistance meets inertia, and the slide pauses momentarily.

    - This is extremely important. If the slide doesn't pause long enough, it can actually overrun the next round up in the magazine! This is also why weak magazine springs cause malfunctions. Shorter 1911 pattern pistols like the Officer's have less inertia in their slides, which make them more dependent upon springs for the same power ammo, and make them more sensitive to changes in their working environments and tolerances than the 5" version of the same model.

    3. After the pause, resistance overcomes inertia. The energy stored in the recoil return spring moves the slide forward, stripping the next round from the magazine and loading it into the pistol's chamber.

    All's well, right? Well, no. Remember inertia? Your firing pin is an inertial firing pin, meaning it cannot touch the round's primer and the hammer at the same time.

    So, now that we have forward inertia, the inertial firing pin slams into the round's primer as soon as the slide and barrel lock and slam suddenly to a stop. Buuuuuuuurrrrrrrrrrrrrp! A firing pin in motion tends to stay in motion, and all that. The feds frown on runaway guns as fully auto.

    Therefore, the firing pin must have a spring to arrest its forward inertia, as well. In addition, a strong firing pin spring keeps firing pin wipe from happening: The firing pin must not be in contact with the primer when the spent round is ejected.

    So, upon firing a 1911, one squeeze of the trigger does this:

    1. The hammer drops, hitting the firing pin.

    2. The firing pin slams forward under inertia. Some of this energy is stored in the firing pin return spring to return the firing pin to rest after the job is done, so that the above listed problems don't manifest.

    3. The round ignites, and recoil begins moving the slide and barrel assembly backwards. The recoil return spring begins storing energy from the ignited round.

    4. The barrel and slide move backward together about 1/4", providing enough energy to overcome the inertia of the hammer and start it moving backward.

    5. The barrel and slide unlock after a safe dwell time and the round is ejected.

    6. The slide continues rearward, fully cocking the hammer.

    7. The slide pauses momentarily at full rearward travel.

    8. The slide begins forward under the stored power of the recoil return spring. Before the slide can get up much forward velocity, it is slowed again as it strips the next round from the magazine. This is very important.

    9. Due to the engineered slowing of the slide, it comes forward to a soft stop.

    - This is why it's OK to chamber a round from a magazine, but not to drop the slide on an empty chamber! A slide dropped on an empty chamber is not slowed and will batter the lugs and cause the sear to bounce. It strains the gun.

    10. The pistol is now ready to fire again.

    Hopefully you now understand why a radical departure from stock weight springs is not a good idea, generally speaking. Yes, some do this, but generally for gaming, where they're firing reduced loads and have matched the springs to those loads.

    The reduction of the mainspring reduces the amount of dwell time. The mainspring is very important to recoil management in the pistol. Reducing its weight reduces the ability of the pistol to handle full-power loads.

    Increasing the recoil return spring's weight allows the slide to slam forward faster and harder than designed. If you're using weak magazine springs, you may have problems feeding, though this isn't an issue on Government-sized pistols as much as it is on shorter, smaller models. If they ever start using aluminum slides, it will be a problem on Government-sized 1911s.

    An increased recoil return spring will also make the slide return faster, potentially battering the lugs and possibly causing sear bounce, which damages the sear nose and could potentially fire the pistol if said pistol has iffy engagement of the hammer hooks to the sear nose, including but not limited to short hammer hooks or negative sear engagement.

    Hopefully this has helped someone.



  2. #2
    Senior Member  
    Join Date
    Kingfisher County, Oklahoma
    Good food for thought.

    If the ends sought cannot be achieved through the means granted to the Federal Government in the Constitution, there is neither a need nor the power for the Federal Government to get involved.. B.E.Wood

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