1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Making a S&W 637 hammerless????

Discussion in 'Gunsmithing and Repairs' started by RH Factor, Jun 4, 2003.

  1. RH Factor

    RH Factor Active Member

    I recently bought a S&W 637 airweight. It is the style WITH a hammer. If ever I decide that I'd like to have a hammerless model, (without bobbing the hammer) can I just buy a new hammer. The style used on their concealed hammer (or hammerless) models and have it installed? Is the frame and the rest of the workings the same? Just wondering.
  2. dfariswheel

    dfariswheel Well-Known Member

    If you can find a hammer of the same type and version, yes.
    For instance, you will need a new version hammer for the guns with the frame-mounted firing pin, etc.

    As a general rule of thumb, a "J" frame hammer is USUALLY interchangeable between most "J" frame guns. Find a new model S&W "J" that uses a spurless hammer, and that hammer SHOULD fit your gun.

    If you can find one, usually the part will fit and function perfectly, WITH some minor fitting. S&W hammers are NOT 100% drop in parts.

    Again the replacement must be a correct version to interchange.
  3. 9mmepiphany

    9mmepiphany Moderator

    if you already have a decent trigger pull, you risk losing it when you change hammers. fitting a new hammer would, in all likihood, mandate a refitting of the original hammer if you wanted to switch back.

    having this in mind, the route i'd follow would be to have the spur of your hammer ground off... or just have it reshaped. if you want the spur back, get another hammer fitted...that way you save a trip to the gunsmith.
  4. Mike Irwin

    Mike Irwin Well-Known Member

    One other thing...

    If you install that type of hammer, you lose the single-action feature of the 637.

    S&W's hammerless guns are double-action-only, they have no single-action sear.
  5. Jim K

    Jim K Well-Known Member

    Another factor is that the J frame hammers are already small and light. If weight is taken off, momentum is reduced and misfires can result with hard primers. This is a point to consider, especially when bobbing the hammer is combined with a "trigger job" that reduces mainspring tension.

  6. E357

    E357 Well-Known Member

    Well yes and no, the mainspring transfers Energy to the hammer and Since the hammer is lighter their is a more efficient transfer to the firing pin. This is because less energy is used to overcome the enertia of the heavy hammer. Now the question we need answering is the primer going off based on energy strike or momentum transfer?

    I vote for quick energy strike since I never set one off by crushing one in my reloading press.

  7. Al Thompson

    Al Thompson Moderator Staff Member

    E357, I have to respectfully disagree. I have bobbed a few hammers and have had ignition problems. IMHO, just bobbing enough to get rid of the "fishhook" works OK. Smoothing out a bobbed Ruger SS gave me the dreaded "clickclickcliks".
  8. E357

    E357 Well-Known Member

    thanks AL, experience is always better than guesswork. I did a 625, but it was easy to play with the mainspring.

  9. Mike Irwin

    Mike Irwin Well-Known Member

    "the mainspring transfers Energy to the hammer and Since the hammer is lighter their is a more efficient transfer to the firing pin."

    Uhm... Not sure what you mean by "efficient," but those who say you can compromise reliability are correct.

    Think of it this way... A bowling pin match.

    The bullet is the hammer, the bowling pin the primer.

    A heavier bullet at a slower velocity (such as the .45 ACP), is usually MUCH better at taking the bowling pins off the table than a lighter bullet at a higher velocity (such as a 9mm).

    By the time you raise the velocity of the light bullet high enough to compensate for the loss of momenum (IF you can safely raise it high enough), you've got recoil that's tough to handle.

    Similarly, in the revolver, by the time you raise hammer speed sufficiently to counteract the loss of momentum, which you have to do by increasing the power of the main spring, you've got a trigger pull that's hard to handle.

Share This Page