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Thread: Action Spring Analysis

  1. #21
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    Quote Originally Posted by Clint View Post
    Double check those lengths and forces on the A5.

    Looks like a dup.
    For the Colt rifle spring, I used the force and L1 length from the drawing, not measured. For the Colt A5 spring, I used the measured force and L1 length from the carbine L1. For the Tubb spring, in the rifle and A5, I used the measured force and L1 length from the carbine L1.

  2. #22
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    Quote Originally Posted by jmart View Post
    So reading your data, I see that the Tubbs flatwire CS spring is stressed the most, but even at mid 40%, it still has a significant margin.
    Springs cycle and don't have to get to 100% to fail. Anything up to about 45% is generally considered a reasonable spring design.

  3. #23
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    Quote Originally Posted by rsilvers View Post
    For the Colt rifle spring, I used the force and L1 length from the drawing, not measured. For the Colt A5 spring, I used the measured force and L1 length from the carbine L1. For the Tubb spring, in the rifle and A5, I used the measured force and L1 length from the carbine L1.
    Is the fourth column "lbs @ 6.902" the force at the installed length or just an arbitrary reference length?
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  4. #24
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    6.902 inches is the length of the spring when installed in a carbine stock.

  5. #25
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    Quote Originally Posted by rsilvers View Post
    6.902 inches is the length of the spring when installed in a carbine stock.
    Yes, but the A5 installed length is .75" longer.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  6. #26
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    That does not matter. The stress is determined at the full recoil position. You can establish the spring rate at any value of L1.
    Last edited by rsilvers; 12-10-11 at 17:06.

  7. #27
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    true, if you're only interested in %MTS.

    The chart also appears to show the useful in-battery/L1 force that many are interested in.

    If a person were to read it this way, the A5 values would be misleading.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  8. #28
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    That is right - the installed force of the springs in the A5 section are not the actual force in an A5, and so one could not use them to help pick a spring based on your desired force by looking at the indicated force. All I was trying to show was the % of MTS at full recoil, which is an predictor of fatigue and spring life.

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