Sigma trigger work (pictures)

[99Mustang]

I joined the forum recently after looking for info on improving the trigger on my 9VE. The post by Erich put my mind at ease about purchasing the gun, but still wanted to improve the trigger from stock. I've seen several posts from new Sigma owners and decided to share some pictures of the work I performed. I hope others find this useful. My first time posting w/pictures so bear with me...

Tools you need: various size punches (I used hex keys), small hammer, dremel, cutoff wheel, polishing stone

The gun in question...

Removal of pin holding the sear housing block assembly, use a punch to know it out from either direction...

The sear housing block assembly removed from the frame...

The metal frame partially removed from the plastic frame (shows orientation, helpful with re-assembly)...

The metal frame, cam side up, showing the two pins ready to be removed. Pay close attention to spring removal, they may pop off and you don't want to lose them. Also, the two pins only go in one way...

Pins removed, sear block removed, springs still in metal frame...

All the pieces disassembled...

The sear block. Polish the cam surface (curve on left hand side) using polishing stone (use a light touch). Polish the surfaces. Smooth out the inside of the slot, I didn't have a polishing tool that would fit the slot, so I used a hardened hex key to smooth out the high spots in the slot...

The pigtail and main spring. I cutoff about 1/8" off both using a cutoff wheel, the ends that where cut are pointing down in the picture...

Picture of the cutoff wheel and pigtail spring. I used a small needle nose to hold the spring, apply light pressure so you don't damage the spring. Run the dremel at it's lowest speed, touch the spring to the flat side of the wheel for short burts of time. You want to take off small amounts of metal at a time. WEAR EYE PROTECTION!

Shows both pigtail and main springs after I removed about 1/8" from each. Note that the springs are flat where the metal was removed...

Reassemble everything, making sure to mount the cut portions of the springs in the tab in the metal housing (you want to leave the untouched ends so they make contact with the sear block). The bottom spring makes it difficult to re-assemble the metal frame to the plastic frame, I used a broken toothpick to hold it in place to the metal frame, then I could slide the metal frame into the plastic frame. It has a tendency to pop out, so be patient...

Closeup of the bottom spring once the metal frame is attached to the plastic frame, see how one tail contacts the metal frame and the other tail contacts the plastic frame. If the tabs aren't installed properly, there won't be any tension on the spring and the sear block will not return to it's rest position (touching the plastic cam surface)...

Next two pictures are of the cutoff wheel and polishing stone. My #1 suggestion is to take your time...

Hope this helps and sorry if the post is too long, I have many more pictures and tried to cut it down to what was pertinent. Good luck to all. If anyone has specific questions I did not cover, feel free to email me via the addy in my profile.

 

[DMark]

So - Did this help your Sigma trigger?

 

[99Mustang]

Quite a bit. Much smoother pull all the way thru, before you could definitely feel the starts-and-stops in the trigger. Weight is now down to 7# - 8#, stock on mine was probably 10# to 12#. Gun remains very reliable, not one FTF/FTE in 700 rounds (used UMC, Blazer brass and non-reloadables, Federal JHPs).

The grittyness of the stock trigger was the thing I couldn't stand, the pull weight was secondary. I'm not finished with smoothing out the sear block slot, I just need to find a polishing tool that'll fit.

 

[J.R. Bob Dobbs]

Great detailed report!! I will probably be doing this to mine as the heavy trigger fatigues my finger quickly.

Do I read this correctly, that you have live-fired the gun AFTER these mods with no trigger-reset problems (700rds)? And you've left the lone spring with the tabs unmodified? I think some folks are calling this the pigtail spring, while others are referring to one of the paired (inner/outer) springs. Some folks have posted about removing one or more of these springs without clarifying which springs, and some have reported reset problems under live-fire conditions after spring removal. I much prefer your method of slightly shortening them.

Also have you actually measured the trigger weight? I'm definitely not wanting to criticize here, just looking to clarify.

I suspect that some shortening of the Striker and Striker Return springs would also be tolerated, and also have a significant effect on the pull. Of course how much is too much......

Good work!

 

[Kawabuggy]

There is another post here:
http://smith-wessonforum.com/eve/forums?a=tpc&f=5201039...961052282#8961052282
That link will cover most of what the pictures show here. The pictures really help to understand what is contained in that link.

To give you the short version, I will cover what I did to mine. Your results may vary.

There are 2 sear springs-a smaller diameter inner spring, and a larger diameter outter spring that contains the smaller spring. I REMOVED THE LARGER SPRING ENTIRELY.

The small spring that is wrapped around the lower sear spring- I REMOVED THAT SPRING ENTIRELY.

I replaced the striker spring (inside the slide) with the Wolff Reduced power striker spring Midway part #295637.

I polished the sear where it touches the plastic sear ramp, the striker head, and sides of the sear where it touches the sear bracket, and the sear slot where the pin rides/pushes on the sear.

Doing these things has SIGNIFICANTLY altered the trigger pull. It is MUCH easier to pull the trigger. I would **GUESS** the pull to be in the 4-5# range. Polishing the sear made the pull much smoother and quite predictable. It is a different gun! Night & day difference.

I have experienced 1 FTF out of 150 rounds. Again, your results may vary.

 

[99Mustang]

Originally posted by J.R. Bob Dobbs:
Great detailed report!! I will probably be doing this to mine as the heavy trigger fatigues my finger quickly.

Do I read this correctly, that you have live-fired the gun AFTER these mods with no trigger-reset problems (700rds)? And you've left the lone spring with the tabs unmodified? I think some folks are calling this the pigtail spring, while others are referring to one of the paired (inner/outer) springs. Some folks have posted about removing one or more of these springs without clarifying which springs, and some have reported reset problems under live-fire conditions after spring removal. I much prefer your method of slightly shortening them.

Also have you actually measured the trigger weight? I'm definitely not wanting to criticize here, just looking to clarify.

I suspect that some shortening of the Striker and Striker Return springs would also be tolerated, and also have a significant effect on the pull. Of course how much is too much......

Good work!

Yes, I've fired 700 rds AFTER the trigger work, all went bang as desired. I left the lower spring (some call this the pigtail) in place and unmodified. I use the "pigtail" term for the inner spring in the inner/outer spring pair.

Yes I've measured trigger weight using a RCBS premium trigger pull gage (mechanical), I get between 7.2# and 8# depending on when I measure. This tells me that the trigger probably still needs a little work to smooth things out, but for now I'm happy with the results. Unfortunately I did not have a scale before I did the work so the 10# to 12" stock is just a guesstimate, I did hang a 10# weight on a string tied to the trigger (very crude) and it did not fire the trigger so it was definitely over 10#.

I agree changing the striker spring would probably reduce trigger pull, but I worry about light primer hits. I did a very little bit of polishing of the trigger and striker sear contact surfaces but was hesitant to do too much. I definitely think some change to the contact angle between the sear sufaces will help, but not sure I want to take this on just yet.

Thanks for the kind words.

 

[J.R. Bob Dobbs]

Thanks again (both of you) for detailing your work.

Kawa's 3.5lb Wolf striker spring seems to be right on the edge of perfect reliability (one misfire out of 150rds).

So perhaps shortening the stock striker spring to make it's tension halfway in between Factory and Wolf would be "it". I could do this given enough motivation....I'd use a Wolf spring, stock spring, precision scale, and some sort of rig to measure compression force at a given deflection, probably consisting of a screw, nut, and sleeve.....and a few beers.

 

[presspics]

I did a trigger job on my SW9GVE today. I did look at the striker spring and it DOES NOT appear to have enough length to tolerate being cut. I would recommend against cutting it.

 

[xrated]

I did a mod on my 40 and 9mm, minus cutting the springs.
#1, threw away the longer spring and kept the smaller one. IE: used only one spring, also threw away the tiny third spring, forgot whats its called.
The Trigger is now very friendly for target shooting now, very very accurate, and no more finger pain. Be carefull, its now very light!
Very light pull, remembering its still a 2 stage, not like a 1911, its now 10 times better, believe me!
Forget the Dremel cutting and polishing, not needed, and you'll be very happy target shooting with this mod I discovered and tested.
Thanks for the photos above, they should help.

PS: 1000 rounds thru my 9, not one misfire, jam, nothing since the mod, haven't even cleaned it. (have added some oil every now and then)
Think I'll clean it this week now I know this weapon is indestructible.
Probably shot 200 rounds on my 40, no problems either.

 

[OKFC05]

Since wersions fo these modifications to the Sigma action keep getting posted over and over, I guess it bears repeating the warning that should be posted with it.

CAUTION: Cutting and removing springs in the Sigma sear assembly may result in failure of the sear to reset when shooting hot defense loads (think single shot).

Although these modifications are IDPA legal and appear to work with moderate loads, there is no guarantee the gun will function normally with defense loads. The outer sear spring was added to the design in response to instances of the sear failing to reset with defense loads. No amount of shooting with moderate loads will indicate whether the gun will function with defense loads.

I am an IDPA match director and researched the safety issue with S&W when the mods started showing up at matches. The failure mode is simply that the gun fails to fire, so it is IDPA legal.

Naturally, S&W does not recommended such modifications for defense use.

 

[haycreek]

Excellent photos and explanation, 99mustang.
Here is a slightly different method.
First, I polished the sear to a bright finish, then, instead of cutting both coil springs, I replaced the larger diameter spring with a lighter weight spring, of the correct diameter to fit over the smaller spring, and trimmed one end to the length of the original larger spring. re-assymbled all three springs, lubed the sear and opposing surface with CLP, and reassymbled the pistol. Results are amazing. The lighter weight larger spring does not 'stack'just before the sear breaks, like it does with the heavier spring. Guess where I procured the "lighter" larger, spring that slips over the smaller spring-----from a BALL POINT PEN. The "over" spring prevents the smaller coil spring from coiling crooked, off to one side, like it would if the larger spring was discarded. I don't have a trigger pull guage, but the trigger is now very acceptable for a double action pistol.

 

[DMark]

..... from a BALL POINT PEN....

Oh Man I have GOT to try that!

That 25 cent Glock trigger mod has nothing on the Sigma free ball point pen spring mod!

 

[haycreek]

It was necesary to look at several ball point pens, until I found one that was exactly the correct diameter.

 

[mcouture]

Originally posted by haycreek:
It was necesary to look at several ball point pens, until I found one that was exactly the correct diameter.

Haycreek, can you recall what pen brand/style it came from? After these months past, has this mod still been OK?

 

[bullitt1668]

Originally posted by haycreek:
Excellent photos and explanation, 99mustang.
Here is a slightly different method.
First, I polished the sear to a bright finish, then, instead of cutting both coil springs, I replaced the larger diameter spring with a lighter weight spring, of the correct diameter to fit over the smaller spring, and trimmed one end to the length of the original larger spring. re-assymbled all three springs, lubed the sear and opposing surface with CLP, and reassymbled the pistol. Results are amazing. The lighter weight larger spring does not 'stack'just before the sear breaks, like it does with the heavier spring. Guess where I procured the "lighter" larger, spring that slips over the smaller spring-----from a BALL POINT PEN. The "over" spring prevents the smaller coil spring from coiling crooked, off to one side, like it would if the larger spring was discarded. I don't have a trigger pull guage, but the trigger is now very acceptable for a double action pistol.

Do you remember what kind of pen you used?

Thx,

Bullitt

 

[thamesb]

I did the same thing as Haycreek did. What an amazing difference. I was tempted to get rid of my Sigma, but know i realy enjoy shooting it.

 

[Deltaboy]

Be Smart Be safe and send it back to S&W per the Free Sigma trigger fix thread. It preserves your warranty and it is FREE. Some of this Shadetree gunsmithing ya'll keep suggesting scares the hades out of me.

 

[idontmiss]

I just wanna say thanks to the people who take the time to help other people like me out with the info u have through out your experiences with your guns and the info u gave on the trigger job for the sigma was perfect I have a sw9ve and it took me 10 mins to do mine and I live it I think it has to be as good if not better than my glock 9mm that they say runs neck and neck with the sigma this gun I think is my new fav out of all my guns because of the trigger job and again thank u for your time and info people

 

[piratriot]

I also performed this mod:

I took out the larger outer spring, and left the inner spring. I also took out the stubby spring on the bottom. (Here is an image of the stubby spring: http://screencast.com/t/xhHiycUUVeA )

So, at this point, all i have is the smaller/inner spring.

Although the gritty trigger problem is not caused by the springs, much of the 'felt' gritty trigger pull is gone after removal of those two springs. I found no need for polishing any parts after removing the springs. It's good enough for me.

The trigger pull is at least half of what it was before.

I haven't fired any live rounds yet. When I do, I will come back and report on my experience.

After I fire some live rounds, I may try using the ball point pen spring that I found in my desk. It's exactly the same diameter as the stock large/outer spring and will slip over the smaller/inner spring easily. I like the idea of using another spring to 'hold' the smaller/inner spring in place.

After I try this ball point pen method I will report back.

Thanks to the original posters!!! The SW9VE is a much better gun after this modification.

This post is worth repeating:

Since wersions fo these modifications to the Sigma action keep getting posted over and over, I guess it bears repeating the warning that should be posted with it.

CAUTION: Cutting and removing springs in the Sigma sear assembly may result in failure of the sear to reset when shooting hot defense loads (think single shot).

Although these modifications are IDPA legal and appear to work with moderate loads, there is no guarantee the gun will function normally with defense loads. The outer sear spring was added to the design in response to instances of the sear failing to reset with defense loads. No amount of shooting with moderate loads will indicate whether the gun will function with defense loads.

I am an IDPA match director and researched the safety issue with S&W when the mods started showing up at matches. The failure mode is simply that the gun fails to fire, so it is IDPA legal.

Naturally, S&W does not recommended such modifications for defense use.

 

[Mike Boyd]

After Mr. Smith got done . . .

Be Smart Be safe and send it back to S&W per the Free Sigma trigger fix thread. It preserves your warranty and it is FREE. Some of this Shadetree gunsmithing ya'll keep suggesting scares the hades out of me.

After I got it back from LSG, it was better, but still gritty and still almost 9#. I read another thread with pictures
http://www.thefirearmsforum.com/showthread.php?t=53874
and took it apart and polished everything with a dremel polishing wheel and fine jeweler's rouge, to a high gloss. I left the original two trigger springs in place and removed only the pig tail spring that is retained by the stainless pin that puts extra pressure on the entire assembly. As I reassembled I lightly lubed all possible contact surfaces with a Constant velocity joint hi temp moly lubricant and wiped away excess to avoid powder and ash build up. I believe the grease sticks to the plastic, where it comes into contact with the metal sear much better than gun oil. Once it was reassembled, it measured less than six pounds and was as smooth as my Cougar 8000 on SA.

My grandson and I put nearly 100 rounds through it tonight with absolutely no problems and much better accuracy, close to what my Cougar .40 shoots. He is 13 with fairly small hands and said he now likes the Sigma the best of all our pistols, since the trigger is now silky smooth, breaks cleanly and evenly with no FTF of FTE with either WWB 180 and 165 and Brazer Brass 180. We will continue to shoot the heck out of it and will keep you posted on reliability results