S&W 640 Trigger pull

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  • SAILORGOLF46

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    20   0   0
    Feb 14, 2012
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    Greenwood
    I recently bought a Mod. 640 nd S&W that has been shot very little. The trigger pull is pretty stiff, should I change springs or will is get better with range time and dry firing? Thanks in advance for help with this.
     

    sloughfoot

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    Apr 17, 2008
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    Dry fire it. Develop strength in the trigger finger and smooth out the action at the same time.

    A trigger job is nothing more than accelerating wear in the contact points of a revolver.
     

    Drail

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    Oct 13, 2008
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    Consider that if someone is about to kill you or a member of your family - you will not notice the trigger pull weight - at all. Trust me. On a range gun used for target work? Sure. On a CCW gun? Doubtful. As long as it fires 100% the pull weight is really not that big a deal. On a S&W J frame you are not going to get as much reduction either by replacing springs or by polishing as you get on a K,L,N frame simply because of the geometry of the trigger linkage. Smaller parts will have less leverage over each other. It is what it is. It's a J frame. It's not a target revolver. Keep the stock weight springs in it and build up your finger strength. Lightening the springs will produce misfires with certain brands of ammo.
     
    Last edited:

    45fan

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    I frequently carry a 442. Basically the same gun, only blued. After putting a few rounds through it (probably close to 1K) it started light striking primers, and not going off. After a bit of digging, I found several sources that cited a shorter than optimal firing pin from the factory as a possible culprit (installed for safety reasons). I replaced the firing pin with a cylinder and slide long pin (+ .1 length, IIRC) While I was in there, I went ahead and replaced the springs with the wolf spring kit, and cleaned things up a little. While shooting did improve the trigger, the pin and spring replacement did work wonders for the trigger, and resolved the light strike issue at the same time.
     

    throttletony

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    Jul 11, 2011
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    I've done the Wolff spring swap on rugers with good success, I hear about similar success on S&Ws

    I always opt for the middle weight springs if 3 are availabe - to avoid lightening it too much. this plus polishing internals will smooth and lighten it.
    Although, honestly, none of that is necessary, it's nice
     

    sliptap

    Sharpshooter
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    8   0   0
    Jan 25, 2013
    307
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    Indianapolis
    I recently bought a Mod. 640 nd S&W that has been shot very little. The trigger pull is pretty stiff, should I change springs or will is get better with range time and dry firing? Thanks in advance for help with this.

    There are plenty of videos out there that will show you how to install new hammer/main springs. There are also videos out there on polishing the internal contact points (trigger job).

    Your biggest concern with weaker springs is that you increase the risk of the hammer not making strong enough contact to ignite the primer. Some people are more comfortable with that fact than others; I definitely am not :)
     

    Contender

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    Mar 11, 2014
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    When I have put wolf springs in my s&w's I just changed the trigger spring and original or standard weight wolf hammer spring. This gets them in the 3 - 3 1/2 lb range without worrying about light primer strikes.
     

    45fan

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    Apr 20, 2011
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    East central IN
    When I have put wolf springs in my s&w's I just changed the trigger spring and original or standard weight wolf hammer spring. This gets them in the 3 - 3 1/2 lb range without worrying about light primer strikes.


    The trigger spring seems to help lighten the feel more than the hammer spring does in most guns I have worked on. The biggest problem with the hammer less J frame is the hammers lack of mass, so the spring weight is more imperative to a solid primer strike. Something to keep in mind too, going too super light on the trigger return will make the trigger feel sluggish on the return, and not always reset reliably. Tuning the trigger pull on a revolver is a balancing act, between smooth, light, and reliable. But once you find it, you will be in heaven.
     

    Hopper

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    Nov 6, 2013
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    Hamilton County
    Sorry to revive a nearly-dead thread, but wanted to add that I saw this right before I picked up a brand-new 640-3. I completely agreed with the OP that the factory DA trigger pull wasn't what I was expecting at all. Crisp break, but a really heavy pull.

    Anyway, after reading this, I ordered the Apex kit for J-Frames from Midway. Just got it this afternoon, and after watching the videos, installation was about as hard as putting Legos together. Probably the hardest part was the trigger rebound spring, as I don't have one of those fork-shaped tools for revolvers. Not hard, just had to go slow to seat the new spring. I did just a little cleaning while I had the side plate off, and very lightly polished the rebound trigger spring guide along the bottom/side per the video's recommendation.

    I'm really, really pleased with the difference it made. Still needs to be shot in a bit, but the initial improvement was well worth the small investment in the kit, and the time it took to install it.
     
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