S&W 31 DA trigger tight

[DaTerminat'r]

Hi,
Just bought a S&W 31 with pinned barrel a few weeks ago. I've dried fire it alot to smooth out the DA trigger, but to no avail. About half way thru the pull, trigger gets heavier. It almost feels like something is binding. Then about 3/4 thru the pull, trigger gets lighter. SA trigger is fine. Below is what I've tried:

(1) The left side of the hammer has scratch marks, so I filed down the frame where the hammer might be touching. It didn't make any difference.

(2) I removed the cylinder, held the thumb piece back, and pulled the trigger. The binding is still there.

(3) I removed the main spring and hammer, and pulled the trigger. No binding at all.

Any ideas?

 

[chief38]

It's tough to diagnose without seeing the gun, but I would guess you have a defective hammer, or hammer stud. How does the side plate fit? Are there excessive wear marks on the inside of the side plate? Which side of the hammer has the wear marks?

 

[Hondo44]

Put the hammer back and leave out the mainspring. You'll be able to feel what's going on easier when not under spring tension.

If you still feel the binding I suspect the DA sear (that 'lever' under spring tension pinned to the front of the hammer) is not fit properly; i.e. a little too long and binding on the trigger. Watch the engagement of the trigger and that DA sear as you pull the trigger with the sideplate off. Do you feel the binding as the trigger engages the DA sear?

 

[DaTerminat'r]

Red is my response.

It's tough to diagnose without seeing the gun, but I would guess you have a defective hammer, or hammer stud. How does the side plate fit? Good. Are there excessive wear marks on the inside of the side plate? No. Which side of the hammer has the wear marks? Left.

 

[DaTerminat'r]

Red is my response.

Put the hammer back and leave out the mainspring. You'll be able to feel what's going on easier when not under spring tension.

If you still feel the binding I suspect the DA sear (that 'lever' under spring tension pinned to the front of the hammer) is not fit properly; i.e. a little too long and binding on the trigger. Watch the engagement of the trigger and that DA sear as you pull the trigger with the sideplate off. Do you feel the binding as the trigger engages the DA sear? No, not with the spring out.

 

[ombesb]

Assemble everything once except for the side plate. Run the trigger through and see if the trigger return slide runs into the main spring, indicating that someone may have tried bending the spring to reduce tension. I have seen this before.

 

[Hondo44]

OK, I think the parts are fitting together just fine, and there's nothing wrong. Some of these small frame guns just have too heavy springs. I would go to a spring kit like a Wolf from Brownell's. Comes with both lighter mainspring and a couple of trigger return springs to experiment with.

 

[Hearsedriver]

I just picked up a 31-1 that also had a stiff DA pull. I swapped the mainspring with a Wolff reduced power spring and the rebound spring with a 15 lb. Wolff spring. It lightened the SA pull from 4 lbs to 3 lbs. and greatly reduced and smoothed up the DA pull. I also had some drag on the trigger wher it was rubbing one side of the frame. I installed a .003" shim under the trigger to center things up which also improved the overall smoothness.

 

[Hondo44]

Assemble everything once except for the side plate. Run the trigger through and see if the trigger return slide runs into the main spring, indicating that someone may have tried bending the spring to reduce tension. I have seen this before.

He said it was a Mod 31. Model 31s, .32 Reulation police (pre mod 31s)and transitional 1st improvement Regulation Police all have coil mainsprings. He would have to have a pre war or transitional post war to have a flat leaf spring. BUT, if he does have a flat mainspring the most common problem is a spring tension screw turned out too far.

DaTerminat'r, what kind of spring do you have; coil or flat spring?

 

[chief38]

Have you tried the DA pull with the grips off the gun? I have seen grip escutcheons mounted slightly off - enough so that the grip screw interferes with the main spring. I had a M19 like that and had to modify the grip screw to correct the problem. The problem was with the grips, not the gun, so try that if you haven't already. Difficult to diagnose this over the internet without actually feeling what exactly is happening.

Chief38

 

[DaTerminat'r]

It has a coil spring. Me cheap; I just trimmed off 2 coils from the spring. Trigger got better; it is usuable now. But the tightness is still a wee bit noticeable. It actually feels alot like my Ruger SP101 trigger, which I don't like Maybe I'm expecting too much from these little J frames. I've been shooting alot of custom PPC revolver with mega smooth trigger lately. Maybe it spoiled me.

 

[Hearsedriver]

I have 5 J frames and all of them have ultra smooth triggers. It is obtainable with a little work.

 

[ombesb]

He said it was a Mod 31. Model 31s, .32 Reulation police (pre mod 31s)and transitional 1st improvement Regulation Police all have coil mainsprings. He would have to have a pre war or transitional post war to have a flat leaf spring. BUT, if he does have a flat mainspring the most common problem is a spring tension screw turned out too far.


Thank you for the polite learning curve, I have been inside numerous n-frames and thus made an unfruitful assumption.

 

[DaTerminat'r]

I have 5 J frames and all of them have ultra smooth triggers. It is obtainable with a little work.

That's what I thought. My other 31 is from Banga Punta era, and I bought it like-NIB and it has very smooth DA. This 31 is pre-BP, so it's suppose to be good, right? But the DA trigger is not. To be fair, the SA trigger is better on this 31.

 

[Hondo44]

I have 5 early 1950 vintage .32s. they all vary somewhat. The most pristine has the worst DA of all of them, which is OK, I don't shoot it much. I only tune my main shooters. I do a standard list of parts checking/polishing. Some come around faster than others and if still not satisfied, I just keep at it 'til I am.

If I have a stubborn one, I study the action as I dry fire slowly with sideplate off to determine exactly which parts are interacting at the moment of bind and focus my attention there. From my experience I still suspect your double action sear is a little long or mishaped on the tip engaged by the trigger. If I'm not sure, before taking metal off I'll substitute another sear and see if it gets better or worse with the different part. It's more patience than anything.

And I, like you, also usually clip springs before buying new ones. I've always believed over heavy springs are used for reliability in the absence of skillful parts fitting.

 

[DaTerminat'r]

I've been dry firing this 31 a lot. And the tightness during the middle of the trigger pull is still there. I've clipped two coils from main spring and two coils from rebound spring. I'm lost. Anyone know a S&W revolver gunsmith near Houston?

When I work the action with the cover off, I think I can see two contact that look suspicious. First, the bottom of the hammer's toe contact the trigger. Second, the double action sear on the hammer contact the sear shelf on the trigger. Seems to me, both contact happen too much at the same time. But I'm not entirely sure. I'm thinking of sending it to Clark Custom in LA for trigger job and fix this problem.

 

[Hondo44]

I've pulled the sideplate on a .32 Model 31. Please observe this with sideplate off:

Upon commencing the tirgger pull, the 1st contact should be the DA sear.
2. After only about a 1/4" of hammer nose travel to the rear, the trigger to hammer toe contact will begin.
3. This double contact mode should exist only for about the next 1/4" of hammer travel then the DA sear-to-trigger contact should end.
4. The trigger to hammer toe contact continues for about the entire next half of hammer travel until the hammer drops.

See if you can identify in which step the binding is felt.

Since you're going to send it off anyway, you have nothing to lose by taking off a little from the DA sear at the point where you see wear from the trigger contact. The rule is to always work on the cheapest part to replace which of course is the DA sear.

I'm convinced that's the issue from working on mine. If it works, you've avoided sending it and the repair cost.

 

[DaTerminat'r]

I just got my gun back from a well known gunsmith shop in LA. I asked them to do something about the binding-like feel on double-action and do a trigger job. I got it back, and the trigger pull is not any better. The binding-like feel is still there. And the trigger is not as smooth as I expected it to be. They said the gunsmith couldn't feel any binding. So, I guess my expectation for a little J frame is just too high. Right? Maybe I'm spoiled by custom K frames that has been smoothed by decades of use. No, I've had a brand new little Ruger SP101 with very smooth out of the box trigger pull. Well, I guess a kit gun doesn't need to be shot double action anyway.

 

[Hondo44]

How dissappointing is that!! Well I don't think your expectation is too high. It's like taking the car to the dealer for repairs, for some reason they can't hear "the noise" unless you're in the car with them to point it out! It makes you just want to take a smooth J frame to him and put it in his hand and say, "this is what I want like this" then hand him the bad one and say, "not like this"! Maybe you can still do that. Did you send it and deliver it in person?
Don't give up, try here: Trigger Job: Complete Action Tuning Smith Wesson Revolvers Jerry Miculek DVD
Kuhnhausen's book or jerry's DVD should be helpful.