MP340 trigger job?

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2ndAmendmentNut

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I have had a S&W (no lock variant) 340 for a little over a year. I really like this little beast as a carry gun. Problem is the trigger is truly terrible. I have cleaned the gun thoroughly. Fired approximately 500rds and dry fire practiced with it hundreds if not thousands of times. The trigger is heavy, but the main problem is a rough spot in the trigger that has not smoothed out with use. The rough spot is right after the cylinder locks up and just before the hammer falls. I have owned several other J frames and none of them have had this noticeable spot of roughness in the trigger.

I am comfortable completely disassembling the revolver, but I have never polished the internals of one. I also would prefer to avoid lightened aftermarket springs. The trigger weight is not the problem, but rather the rough spot mention above. Any advice on how to improve the trigger myself? Or any reputable smiths I could send this gun off to for a trigger job that won't compromise reliability?
 
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I feel your pain...or at least, I used to.
I have the same gun and had the same 'rough spot'. My cure was to install a Wolff 13lb trigger return spring and an 8 lb mainspring. It is fine now.
 
The problem may also be linked to improperly fit, or poorly fit ratchets. In this scenario, the hand rubs against the side of the oversized ratchet, or rachets, as it passes by after lock up has ocurred. Unfortunately, this is a vary common problem. Does the action seem smoother if you open the cylinder, hold the thumbpiece back and cycle? If so, this may be an indication that the interface between the hand and ratchet is the problem.

You could have the action evaluated by a trusted, experienced local gunsmith. The other option would be to contact S&W Customer Service and talk to them about a possible resolution. 1-800-331-0852
 
I've once had that hitch cured by a Wolff factory power mainspring, and twice by dressing the ratchets. The posts above are spot on...
 
armorer951 said:
Does the action seem smoother if you open the cylinder, hold the thumbpiece back and cycle?
Click to expand...


The action is significantly smoother with the cylinder open. Still a heavy trigger but no rough spot.

Can I modify or replace the extractor/ratchet to fix this or do they need to be fitted by an experience smith?
 
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I polished the contact surfaces on my M&P340. Like you, I had the same rough place right after the 2nd click which is when the hammer is released.

Here's a thread I put up:
http://smith-wessonforum.com/s-w-revolvers-1980-present/461485-our-j-frames-got-stoned.html

Never had a revolver open before I did this but I'm pretty good with mechanical things. If you want to do it yourself, watch the yoda-g mod video on youtube a bunch of times.

I did not replace any springs in my 340. I don't mind a bit of a pull on a defensive pocket revolver but I DO want smooth. It's now like butter and the final sear release is predictable and instant.
 
This is one of those repair issues that you trust to an experienced, trained gunsmith, experienced revolver armorer, or a factory authorized repair shop. Fitting these parts requires special tools, and a lot of experience. Out of all the fitting operations of the gun, final fitting extractor ratchets is by far the most difficult. With all due respect to the folks on youtube, they can't teach this skill, or provide the necessary tools or experience.

It's your gun, but in this case getting it wrong can make the revolver unsafe or unusable. Do yourself a favor and have it evaluated by a trained, qualified gunsmith or S&W authorized repair center.
 
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armorer951 said:
This is one of those repair issues that you trust to an experienced, trained gunsmith, experienced revolver armorer, or a factory authorized repair shop. Fitting these parts requires special tools, and a lot of experience. Out of all the fitting operations of the gun, final fitting extractor ratchets is by far the most difficult. With all due respect to the folks on youtube, they can't teach this skill, or provide the necessary tools or experience.

It's your gun, but in this case getting it wrong can make the revolver unsafe or unusable. Do yourself a favor and have it evaluated by a trained, qualified gunsmith or S&W authorized repair center.
Click to expand...

What he said...PLEASE! Remember it is a carry piece, not a range gun. 100% reliability is where you start from.

Kaaskop49
Shield #5103
 
What would you all recommend? I don't trust anyone local. A return to the factory? Or a qualified 3rd party smith?
 
2ndAmendmentNut said:
What would you all recommend? I don't trust anyone local. A return to the factory? Or a qualified 3rd party smith?
Click to expand...

The factory will refuse to install lighter springs. In fact, if they are working on your gun and find non-factory springs, they will replace them with originals.
 
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Yeah... if you do this, I wouldn't touch anything on the extractor star. I just barely raked the sharp edges on the "hand" and didn't touch the star.

New springs? I do not recommend replacing any springs since this is a pocket-carry defensive piece which may defend your life some day. I don't mind a heavier pull - to me, it's expected.

But the rest of it? If you've had one open, you can see it's not rocket science. It's not even small engine repair. Just a handful of parts and springs that interact with each other. I did two relatively new j-frames Airweights back-to-back in a span of 3 hours and that's with me not ever having a revolver open before. My training was watching a very good YouTube video plenty of times. I also took a digital picture of the assembled insides, enlarged it, and printed it. With only the hammer spring removed, I carefully worked the insides so I could see first-hand what part did what and marked the contact areas that I would be polishing with different colored pens. I also marked the points that should not be touched.

You DO have to be careful and know what you are doing. Admittedly, tasks like this can be daunting for many. I've always been good at meticulous first-time things like this - especially after watching someone do it.

I wanted to learn this. I was going to learn this. And I used what I learned here to glisten up the trigger feel on a mini 14 and a mini 30.

Me personally... I would not have let anyone but me or the manufacturer do this since the experience levels of a my local gunsmiths (I don't know any personally) are unknown to me. I wouldn't hesitate to send it to Terry at Impact Guns who is shown doing the same trigger job like we are talking about. He passes since I've seen his work: ;)

"https://www.youtube.com/watch?v=I4GtXq2XXOI"

The safe thing would be to send it to S&W for a trigger job - complain about the rough spots (especially the one at the hammer release) and I'll bet you can get it done under warranty or at a reduced rate.

I'm still thrilled with both of ours. They could not have turned out better.
 
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2ndAmendmentNut said:
Would you mind explaining what you mean by "dressing" the ratchet?
Click to expand...
"Dressing the ratchets" is a catch-all term for the process of properly fitting the extractor teeth describe in better detail by armorer951; he's correct, it's a job for the informed and experienced. Even very gentle stoning performed by the mechanically inclined -- which might do the trick -- I wouldn't dare try to explain in a post for fear of the risk of it going astray.

According to the latest iteration of the Kuhnhausen shop manual, oversized ratchets are one of the most common problems with current S&W revolvers leaving the factory, so you're not alone. A qualified revolversmith, or the factory, can address this.
 
Very impressed. One business day later I received a reply via email with a return shipping label and instructions. I'll get my 340 boxed up and mailed out on Monday.
 
Double checked the fed ex tracking number, and the gun has already been safely returned to the factory. Now the waiting begins.
 
I am lucky to have a range master at work who has been trained by Smith on their revolvers. He just dressed up a 386 SCS for me with the same issue, Ratchets. Hope your revolver makes it home soon. They sure are fun to shoot!!

Tony P
 
I have followed this thread and learned a lot.
I have a 340PD that I have owned for many years. The stock trigger is exactly what you are looking for. Reasonably heavy, but very smooth throughout the entire cycle. Exactly what a SD gun should be.
I look forward to hearing the results of it's trip to the mothership.
 
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