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Simple, Zero-Cost Fix for your S&W SIGMA Heavy Trigger Pull

Discussion in 'Handgun Discussion' started by RallyJR, Dec 7, 2009.

  1. RallyJR

    RallyJR Milwaukie, OR Member

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    I caught this tip from a guy who stand strongly by his SW9VE in a sea of Sigma haters.

    One of the largest complaints on the Sigma series handgun is that it has a trigger pull weight comparable to rebar; i.e. very heavy pull.

    Basically, he had found through the grapevine that he was able to slightly modify some spring orientations inside the sear to reduce the weight of the pull down to an estimated 5lb to 6lb pull from the what...12lb factory pull?

    So here it is, I'm performing this on my Sigma .40cal SW40VE, I must prefix this whole thing with an apology for terrible cellphone pics. I suggest doing a couple of dry pulls before and after so you can feel the difference.



    Step 1: Get yourself a Sigma, remove it from its holster, take out the mag.

    img1260241007861.jpg

    img1260241008475.jpg

    img1260241008905.jpg

    Step 2: Remove the Slide, set it aside.

    img1260241009367.jpg

    Step 3: Use a punch to push out the pin at the back of the frame, you can see it below pushed halfway out.

    img1260241009894.jpg

    Step 4: With the pin completely removed, slide the sear housing upward out of the frame.

    img1260241010190.jpg

    Step 5: As the sear housing slides up, pull the trigger to release pressure on it so it can slide free of the frame

    img1260241010858.jpg

    Step 6: You should now have the sear housing free, just this piece shown below.

    img1260241011268.jpg

    Step 7: Remove the ejector, it just pulls free. Pay attention to how it is oriented on the sear housing for re-assembly.

    img1260241011780.jpg
     
  2. RallyJR

    RallyJR Milwaukie, OR Member

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    Step 8: From the bottom of the sear housing you will see another pin with a pigtail style spring on it. Remove that pin, set the pigtail spring aside, and slide the sear out of the housing.

    img1260241012316.jpg

    This is how the disassembled unit should look now.

    img1260241012861.jpg

    Step 9: There is a straight coiled spring that is part of the sear assembly. Actually, on some Sigma's there are two springs there, one inside the other.

    If you have only a very skinny spring that is about 1/2 the diameter of the pigtail spring from step 8, you do not need to do anything with it. Proceed to step 11.

    If you have a spring that is about equal to the diameter of the pigtail spring, then you should have both springs.

    You will now need to gently pry those two springs out of the housing, being very careful not to bend them.

    Step 10: With the two coil springs removed, slide the skinny spring out of the wider one and set the wider one aside. Re-install the skinny spring into its original location. Below is a shot of the wider spring out and the skinny spring re-installed.

    img1260241013978.jpg

    Step 11: We can now address the spring changes. The pigtail spring was added simply to increase trigger pull. It will not be re-used. Additionally, the doubled up spring that you removed in step 10 will not be re-used either.

    Re-assemble your sear into the sear housing without these two springs. Re-install your ejector, and install the sear housing back into the frame. Once this is complete, replace the rear pin into the frame to secure the sear housing into place.

    Step 12: Re-install your slide, and go blow some holes in something!
     
  3. trainwreck

    trainwreck salem Member

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    thank you very much for this write up on how to do this. i just got my sigma 40 all put back together. fells much better now. ill have to go to the rage this week and see how i like now.
     
  4. RallyJR

    RallyJR Milwaukie, OR Member

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    Let me know, I haven't fired mine yet since I did this last week.
     
  5. Trlsmn

    Trlsmn In Utero (Portland) Well-Known Member

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    Thanks Rally Jr that is very helpful. I will give it a try on my brother Sigma this weekend.

    Just one thing I see wrong and please don't be offended but you need to keep the bullets away from the gun when working on the gun.
     
  6. RallyJR

    RallyJR Milwaukie, OR Member

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    After the picture of it being unloaded, you don't see any any mags in the pics do you? :thumbup:
     
  7. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Nice writeup. I'd do just one thing differently. I agree that the "pigtail" spring is there only to increase trigger pull for "safety." The other spring however is the striker spring and I'd be afraid of getting light strikes by that method.

    Midway sells a lighter Wolff replacement spring for that for $6 and I'd buy it and swap to that since it's engineered and tested for that purpose. Link I'd still leave out that pigtail spring.

    I have a friend who did that, and I'd say his trigger is now similar to a Glock. Not bad, not great, but not the animal it was when new. Big improvement. :thumbup:

    BTW, those guns seem to be very dependable - bang every time.
     
  8. RallyJR

    RallyJR Milwaukie, OR Member

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    I can understand the sentiment, I've noticed from other sources though that many have done it and haven't had an issue. I'm hanging onto my springs just in case, I'll definitely be doing some testing...

    Mine actually jams alot. No problem ejecting the spent round, but it isn't pushing the next one up and in very well. Jams at least once on every 10 round mag. A whole different issue for an entirely different thread, however.
     
  9. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Have you tried different mags, done a polish on the feed ramp? My friend's doesn't jam.

    Some say it takes 500 rounds to break those in...

    I forgot to add that he polished his trigger parts too - where they rub - nothing to do with FTF though.
     
  10. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Did you buy it new? How many rounds through it? Could it have a weak slide spring? I replace those every 1000 rounds unless the man. says to do it more often...

    They can fail...
     
  11. RallyJR

    RallyJR Milwaukie, OR Member

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    I haven't really messed with it at all. I've taken it shooting twice, but I received it used and I don't know how many rounds have been through it, but I don't think the previous owner fired it much. Both of my factory mags do it, I'd like to find some hi-caps for it.

    I'd like to go through and polish pieces, but I've never done it before. I could use some good "where to start" sort of education.
     
  12. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Polishing the feed ramp is just a matter of using some 600 grit paper on a dowel until all tool marks are gone, and then polishing with a dremel tool and red rouge. Just lightly polish, and don't dig any grooves with the sandpaper or polish, and maintain the original shape.

    Fail to feed with both mags makes me suspect the main spring for the slide. Not knowing the round count, I'd replace it anyway.

    I've also seen it with reloads which were too "fat." That's usually caused by the final step - the crimp die. If case lengths are uneven, a long case can be bowed out. If case lengths are even but the crimp die is set too low, it can still bulge the case. Mic those cases on the first few loads! At least try dropping them in and out of the chamber.

    I've heard only good things about the reliability of those guns, and only bad things about the triggers until reworked.

    $.02
     
  13. RallyJR

    RallyJR Milwaukie, OR Member

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    I might just up and replace it. This is some feedback I got from the same guy that I got this spring fix from. I might do this at the same time...

     
  14. Radkng

    Radkng Boring, Oregon Member

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    I was looking at midaway they have the guide rod and recoil spring kits available in reduced and plus power. 12-24 lb available, 16lbs from factory.

    They also have the trigger spring, wolff 3 1/2 lb reduced power.

    Would you remove the pigtail spring and use the wolf trigger spring? Makes me wonder if there is a saftey factor of making the pull too light on this type of trigger system?

    -Steve
     
  15. Gunner3456

    Gunner3456 Salem Well-Known Member

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    S&W DA revolvers ship with about a 5# trigger pull and no other safety. The Sigma ships with about a 12# trigger pull for "safety." Please tell me why the lighter pull is OK for a DA revolver but not for an auto?

    12# is simply too much for accuracy imho.

    It used to be that if you complained, you could send the Sigma back and they'd reduce the trigger pull for you. Now they quit doing that.

    The Sigma is a good gun. The military just bought more than 200k of them for Afghanistan in the all black version, in 9mm NATO of course.

    Imho if 5# is enough "safety" for a .357 magnum revolver, it's enough for an auto.

    I'd put in a new stock 16# main slide spring (Wolff is good) because you don't know the round count and because it's failing to push the round completely into the chamber. A new guide rod couldn't hurt either. I'd put in that new trigger spring from Midway and remove that little coil spring. Now you'll have about a 5# trigger pull which is very similar to a Glock or a revolver, and the slide may well return to battery every time.

    The rep on that Sigma is that it goes bang every time and it's accurate. The knock is the trigger. It's not Chinese junk. It's a S&W.

    $.02
     
  16. Gunner3456

    Gunner3456 Salem Well-Known Member

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    BTW, when you get your new main slide spring, if it's longer than your old one, you'll know your old one has failed from cycling. If they are the same length the old one still may have failed, but you'd need a way to measure the compressed strength to know for sure.

    I replace that main spring every 1,000 rounds on an auto. 2,000 rounds is about the outside limit for those springs on a lot of guns. Failure can be almost sudden. It doesn't break, it just gets weak and short.
     
  17. RallyJR

    RallyJR Milwaukie, OR Member

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    I've got a new Wolff recoil spring on the way.

    I've also got a Glock 19 stainless captive rod on the way from Lonewolf Distributing. I'll report back soon on how this works out.
     
  18. PhysicsGuy

    PhysicsGuy Corvallis, OR Resident Science Nut

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    I don't know where you get your facts, but;

    S&W revolvers don't ship with a 5lb DA pull :thumbup:

    Normal production guns have a SA pull of usually somewhere around 5-6lbs, and around 12 or so lbs for DA.

    Also their revolvers do have an internal hammer block safety (not the external lock, that is not a safety device) that prevents the hammer from striking the firing pin (or from falling all the way if the FP is on the hammer) in the case that the hammer falls without the trigger being pulled.
     
  19. Gunner3456

    Gunner3456 Salem Well-Known Member

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    You're right on the trigger pull, my bad. :(

    By "no safety" on the revolvers, I meant of course no safety to stop you from pulling the trigger and making it go bang. :thumbup:
     
  20. Radkng

    Radkng Boring, Oregon Member

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    There is a video on u-tube on removing the pig tail spring, claims that is all he needed to improve the trigger. I tried removing the pigtail spring and only changed the trigger pull by 1 pound or less. The trigger was at 10.5-11.0 with all factory springs after firing 100 rounds throught it, now seems to be 9.5-10.5 with the pigtail spring removed.
    Did not make much of a difference, I will try removing the other spring and test it again just to see how much difference it makes but am ordering a spring from wolff and will test the pressure again with the new spring installed.

    -Steve