set triggers on a lyman great plains

Discussion in 'The Gun Builder's Bench' started by michael mcghee, Nov 8, 2019 at 10:54 PM.

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  1. Nov 8, 2019 at 10:54 PM #1

    michael mcghee

    michael mcghee

    michael mcghee

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    got a problem with the set triggers on lyman.. you set the rear trigger then fire it most of time it stop at the half cock ... it will fire every time if you use the front trigger first... could the lock be rubbing on the stock???? thanks michael
     
  2. Nov 8, 2019 at 11:33 PM #2

    L Rupp

    L Rupp

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    Check the "fly" on the tumbler to see if it is damaged, broken, missing, Ect. That would be the first place I would check based on the problem you are having. It's not likely that the lock is rubbing on the stock to cause the problem you describe.
     
  3. Nov 9, 2019 at 1:02 AM #3

    pa woods roamer

    pa woods roamer

    pa woods roamer

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    Take the Lock out and see if it hangs up then. Might be the Lock screw is too tight, it just has to be snug.
     
    Last edited by a moderator: Nov 9, 2019 at 6:01 PM
  4. Nov 9, 2019 at 1:15 AM #4

    michael mcghee

    michael mcghee

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    no it dont hang up out side the stock.. i try it snug and tight .. some times it goes all the way down sometimes it dont ...
     
  5. Nov 9, 2019 at 2:00 AM #5

    michael mcghee

    michael mcghee

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    i took the lock apart cleaned it still didnt help..
     
  6. Nov 9, 2019 at 4:00 AM #6

    L Rupp

    L Rupp

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    So the "fly" is OK ? It's function is to prevent the sear from catching the half-cock notch when fired using the double set trigger.
     
  7. Nov 9, 2019 at 4:57 AM #7

    michael mcghee

    michael mcghee

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    what does the fly look like??? will the screw between the triggers have anything to do with it???
     
  8. Nov 9, 2019 at 9:00 AM #8

    Phil Coffins

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    The fly looks like a tiny men’s tie, it’s located on the tumbler. The screw in the triggers has nothing to do do with the function of the lock. You need to find a picture of a lock that names the parts so suggests will make since.
     
  9. Nov 9, 2019 at 9:03 AM #9

    Darkhorse

    Darkhorse

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    I would say your sear lever is rubbing on your stock. The Lyman GPR's are notorious about this. Remove the lock and look real close in the hole where your sear lever goes. What you are looking for is a tiny shiny spot in the bottom of the hole. This is where the wood fibers have been compressed by the sear lever, caused by the wood swelling. Take something sharp and scrape the mark away until your triggers again fire the lock reliably. Or you can grind a little off the sear lever as I do.
     
  10. Nov 9, 2019 at 11:27 AM #10

    Ames

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  11. Nov 9, 2019 at 5:27 PM #11

    michael mcghee

    michael mcghee

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    the fly is in it .. how should the fly be in the tumbler?? found a pic of the fly on lyman web sight.. AMES the fly on mine dont look like the one in pic???
     
  12. Nov 9, 2019 at 5:37 PM #12

    michael mcghee

    michael mcghee

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    does it look like the fly is broke??
     

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  13. Nov 9, 2019 at 5:52 PM #13

    Phil Coffins

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  14. Nov 9, 2019 at 6:04 PM #14

    michael mcghee

    michael mcghee

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    there is a sharp edge on one side that why i ask
     
  15. Nov 9, 2019 at 6:15 PM #15

    michael mcghee

    michael mcghee

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    order one on lyman web sight
     
  16. Nov 9, 2019 at 6:17 PM #16

    Zonie

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    It's hard for me to tell with the picture you posted.

    To check to see if the fly is working like it should, reassemble the lock. Then, put the hammer at full cock.

    Place your thumb on the hammer to control how fast it can fall when the sear is released. The sear is the part that engages the full cock notch. It has an arm that sticks out perpinducular to the lock plate. Pushing up on the arm moves the nose of the sear out of the full cock notch allowing the hammer or cock to fall.

    With your thumb ready to resist the force of the falling hammer or cock, push up on the sear arm.

    Carefully watch the nose of the sear as the hammer/cock is falling. It will move until it reaches the fly in the tumbler. If the fly is ok, it will block off or cover the half cock notch and the nose of the sear will jump over the fly and the half cock notch.
    If the fly doesn't keep the nose of the sear from entering the half cock notch, it must be replaced.

    It is ok to shoot the gun using just the front trigger because the force of your finger on the trigger keeps the sear clear of the half cock notch.
    It is NOT OK to shoot the gun using the trigger in the set position with the rear trigger set if the fly is not working like it should.
    Shooting the gun with the set trigger and a defective fly can break the sear and or the tumbler.

    Here is a link to the Lyman site so you can buy a new fly.

    https://www.lymanproducts.com/flintlock-lock-replacement-parts

     
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  17. Nov 10, 2019 at 12:39 AM #17

    Grenadier1758

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    The part is #11 in the drawing. The price is $3.81.

    The test is simple enough. The fly should move easily in its slot. Look for binding of the fly, the tumbler or the sear. Its worth looking for internal dragging of the sear in the sear recess.
     
  18. Nov 10, 2019 at 1:59 AM #18

    michael mcghee

    michael mcghee

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  19. Nov 10, 2019 at 6:45 PM #19

    Larry (Omaha)

    Larry (Omaha)

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    Yes, it is as stated by Phil. Knowing what a fly does will help you in the future. When the lock trips via a single tigger the force on the sear is a longer slower one, keeping the sear from falling into half cock. When you use the set trigger, the energy is quick like a mouse trap. It starts the tumbler to rotate, but doesn't keep the energy force there long enough to keep it from going into half cock. The fly shape pivots allowing the sear to go across the HC notch when bringing the hammer back, but pivots back when the hammer is going forward keeping the sear out of half cock.
    Hope that helps, and the new fly should take care of your problem.
    Flintlocklar:D
     
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  20. Nov 10, 2019 at 11:33 PM #20

    michael mcghee

    michael mcghee

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    thanks larry next question how does it go back in?? mine go in the as the picture in this post???
     

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