S & W Mod 15 Firing pin strike pressure ?

Discussion in 'Revolver Handguns' started by nonferrous, Jul 1, 2009.

  1. nonferrous

    nonferrous New Member

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    I have an older S & W mod 15 that worked fine until the mainspring broke. This happened years ago and I had a gunsmith replace the mainspring.
    When the work was done I put the gun away for a long time untested, I have since moved 1800 miles away from the gunsmith.
    I took it out the other day and the firing pin does not strike the primer hard enough to fire, just a fine dimple.
    When tested and looked at dry, the firing pin travels deeply enough to do the job on the primer and it is sound.
    It looks to me, that the stress screw that acts on the mainspring can be moved to adjust the strength of the hammer blow.
    I am looking for just a little direction from someone that is familiar with this action.
    Thanks
     
  2. masterPsmith

    masterPsmith New Member

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    Tighten down the strain screw. If it is already tight, the smith you took it to may have shortened it for a lighter double action trigger pull (and went too far). If so, replace the strain screw.

    Jim...................
     
    Last edited: Jul 2, 2009

  3. nonferrous

    nonferrous New Member

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    Strain Screw.

    Thanks Jim,
    I just tried it and that strain screw is bottomed, it 's not going anywhere. I will take the grips off of one of my other 'K' frames and compare the screw length on them.
    Thanks again, Len
     
  4. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

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    Main spring tension on a non-magnum S&W revolver should be 3 1/2 lbs. Magnums should be 3 3/4 lbs. Tension is measured by hanging trigger check weights off the hammer at the first notch below the hammer nose. It is easier to do than it is to explain.

    +1 on the strain screw. Tension is adjusted by altering the length of the strain screw. A hack may not get it right.
     
  5. nonferrous

    nonferrous New Member

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    S&W hammer strike

    Thanks for the info.
    I pulled the strain screw and it has been shortened, I thought that trigger pull was too good to be true.
    Anyway, I took a spent large pistol primer, cleaned it and flattened the inside with a small flat bottomed punch, this came out to about .015.
    I slipped this over the end of the screw and the result is that now, the apparent hammer pressure is about the same as my other 'K' frames.
    Next step is to check the actual weight as you have described and then back to the range.
    Thanks again, Len