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  1. #1
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    Model 696 mainspring tuning.

    I have put Trapper (out of business now I think),reduced power spring kits in several S&W revolvers with the outcome being a lighter trigger pull. However, I am having trouble with a pre-lock Model 696 (5-shot .44 Special). It fails to ignite some primers unless I keep the full power mainspring installed. I can take a reduced power mainspring from a L frame or an N frame that performs perfectly in those guns, and when I put that same spring in the 696, it refuses to ignite the primers reliably.
    It has a hammer mounted firing pin, not mounted in the frame. I suspect that the firing pin (called "hammer nose" in the schematics) might be a little short, although it appears to project the same distance through the frame when fired as my Model 686 (which also is pre-lock and has a hammer nose firing pin).
    I have added shims to the mainspring tension screw to give it a little more push, but that results in the trigger pull being as heavy as a standard power mainspring.
    Note: the mainspring tension screw length has never been messed with inasmuch as I bought the gun new, and it is always turned all the way in as it should be.
    Also, I use Winchester pistol primers in all handgun applications.

    Any thoughts as to why a reduced power mainspring would work fine in other guns (L and N), but not work in this one?

  2. #2
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    Re: Model 696 mainspring tuning.

    I can't explain your problem, but I always stay with the std. S&W mainspring. I have changed the Trigger Rebound Spring to 13# Wolff springs on three of my older Smiths.....M-17 K22, M-67, M-10 2" carry piece. I get a smooth, lighter trigger pull, and no ignition problems, with any type of ammo. It will shoot anything!
    I feel that it is light enough for my purposes. The K22 has also had an action job at S&W. It has a really sweet DA trigger pull, and you just have to touch the trigger in SA, to make it shoot!

    I shoot the K22 DA, mostly. The SA pull is so light....it's scary!
    You don't even touch the trigger, before you're ready to shoot. Bob
    When you want the BEST! Bob

  3. #3
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    Re: Model 696 mainspring tuning.

    You don't need to spend money on reduced power main springs. There are many ways to lighten the hammer tension.
    Modify the original spring (cut to weaken or bend to weaken), or adjust the screw.
    To adjust the screw: Put the main spring back in. Then start un-screwing the strain screw until it misfires. Go back in 1/4 turn. Measure the position the screw is backed out.(IE .080 backed out). Now file the strain screw down to set your position.

    Retighten your strain screw and you should have a lighter trigger and 100% reliable ignition with your current ammo selected.

    To lighten the spring:
    Cut strips down the sides to weaken the spring. Or
    Bend the spring to weaken the spring. (when you want reliable ignition you tap it flat before putting them back on).
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  4. #4
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    Re: Model 696 mainspring tuning.

    Quote Originally Posted by 500 Magnum Nut
    You don't need to spend money on reduced power main springs. There are many ways to lighten the hammer tension.
    Modify the original spring (cut to weaken or bend to weaken), or adjust the screw.
    To adjust the screw: Put the main spring back in. Then start un-screwing the strain screw until it misfires. Go back in 1/4 turn. Measure the position the screw is backed out.(IE .080 backed out). Now file the strain screw down to set your position.

    Retighten your strain screw and you should have a lighter trigger and 100% reliable ignition with your current ammo selected.

    To lighten the spring:
    Cut strips down the sides to weaken the spring. Or
    Bend the spring to weaken the spring. (when you want reliable ignition you tap it flat before putting them back on).
    Which does not answer the question: Custom lighter mainsprings and modified one (that I have lightened by the method you describe), works in other guns, but results in misfires in the 696.
    Also, I am willing to spend the few dollars it costs for the correct method of lightening double action pull. But I am not willing to do a hatchet job on the strain screw.

  5. #5
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    Re: Model 696 mainspring tuning.

    What do you thing you have a glock? Revolvers are hand fit. One won't be like another unless the same guy puts it together.

    Below needs to be checked on your L frame....

    Check and or adjust head space to .060"-.068" inch.
    Check and or adjust end shake to .002 inch.
    If you have yoke shake, remove it.
    Is underneath the ejector clean?
    Are you using improperly made reloads?
    The firing pin on your gun could be damaged.
    The strain screw could be modified or replaced on your gun. They come extra long for a reason. After all it's a fitted part.
    See the FAQ above on how the factory armorer adjusts your hammer tension / main spring.
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  6. #6
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    Re: Model 696 mainspring tuning.

    Quote Originally Posted by 500 Magnum Nut
    What do you thing you have a glock? Revolvers are hand fit. One won't be like another unless the same guy puts it together.

    Below needs to be checked on your L frame....

    Check and or adjust head space to .060"-.068" inch.
    Check and or adjust end shake to .002 inch.
    If you have yoke shake, remove it.
    Is underneath the ejector clean?
    Are you using improperly made reloads?
    The firing pin on your gun could be damaged.
    The strain screw could be modified or replaced on your gun. They come extra long for a reason. After all it's a fitted part.
    See the FAQ above on how the factory armorer adjusts your hammer tension / main spring.
    Thank you. This is the type of information I was looking for. I will check head space, end shake.

  7. #7
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    Re: Model 696 mainspring tuning.

    I think your problem is probably a simple fix. I would try a new strain screw, to check if your present one is too short.........or, maybe, the firing pin needs to be longer. It is more important that your gun will fire reliably.....rather than have a light trigger. That, is why I change only the TRS, not the mainspring. Bob
    When you want the BEST! Bob

  8. #8
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    Re: Model 696 mainspring tuning.

    Quote Originally Posted by Bob K
    It is more important that your gun will fire reliably.....rather than have a light trigger. That, is why I change only the TRS, not the mainspring. Bob
    With all but the 696 I have had both, a light double action trigger and reliability. My guns are not carry guns. They are hobby shooting guns (my own range) and nevertheless, have very light double action triggers and are reliable. My carry gun uses a coil mainspring, also a Trapper, and is lighter than the factory.

  9. #9
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    Re: Model 696 mainspring tuning.

    Addendum: I have cut off the hammer spur and polished that area. Testing with my standard hand loads (that I have used for all testing of this gun), the 696 fires without any misfires with the lighter mainspring.


 

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