Wolff Reduced power spring kit...

The factory doesn't hand fit anything now. They take one of each part out of a bin of hundreds and stick it in the gun. Every part in every bin is a little plus or minus off the perfect blueprint size and geometry.

Every gun is a mosaic of all the plusses and minusses of each individual part in it, and how all the tolerances stack up or cancel out, and how they all function together as a whole. Because of this, no 2 guns are exactly alike. The MIM parts are less variable than the forged and machined parts, but still not perfect. No 2 springs are exactly alike, especially the flat ones, due to material, heat treat and bend variables.

All this is why when you're doing an action job, you have to measure what results you're getting to know what's working or not working, and where to go from there.
 
The substitute spring has a groove in it that essentially makes the strain screw shorter, not putting as much tension as it does on the solid original spring. If you do the hammer pull test, you will see the numbers.

If you get a longer strain screw or a set screw and dial the tension on the sub spring to the same tension as the original, you will get the same results in shooting the gun, because then the hammer will be hitting the firing pin with the same force.
 
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I don't understand the fascination with reduced power mainsprings. The last thing I want in a firearm is something that has the potential to decrease reliability, or increase hammer fall time. There are only a couple guns in existence where the stock springs are too heavy for serviceable usage.
 
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Always figured that engineers knew more than me so I leave all my guns the way they come from the factory.
 
Ignition is dependent upon the force with which the firing pin strikes the primer

This force is cumulative , including the cumulative friction losses of the moving parts .

Weight per se is Not the most important factor in a trigger pull . Smoothness and consistency are . A smooth 12lb is much superior to a rough and inconsistent 6 lb .

Stock springs with extra slick internals are usually better than an average new ( or low milage) gun with reduced springs . Slickness of internals can come from lots of shooting , or judicious stoning .

Sufficient ummph from the trigger return spring is important for rapid DA work , and smooth functioning generally .

I'll add a small caveat to S&W Engineers knew what they're doing , and leave stock .

Occasionally by the sheer odds , tolerance stack could add up all in the wrong direction .

My amended suggestion is to keep within Factory Specifications - On most centerfire , between 8 lb to 12 lb .
 
OK Then, now I have a question;

I'm about to do my own action job on my NIB Model 686-6 6" 357. I'm gonna do the usual to clean up factory burrs and the like from the frame and trigger, hammer, cylinder stop, return spring and slide, just a Level 1 type action job (not looking for something fancy) looking for about a 10Lb DA pull, and the single action wherever it decides to land. Instead of using my Wilson Reduced power main spring (but maybe use the RP return spring), couldn't I just shorten the Factory strain screw (if needed) and still use the Factory main spring to get to my 10Lb DA pull (that's what I ran in my Smith Model 66 when I was shooting IPSC in the 70's and 80's and was very comfortable with that DA pull) ??? Right now I'm guessing I have a STOCK DA pull in the neighborhood of about 15Lbs (judging by feel of my Taurus model 66 7 shooter with a measured DA pull of 13Lbs) and not quite as smooth as my stock Taurus model 66 pull. All my equipment/tools are in storage right now so I can't be more specific on the measurements I gave for my 686, just a guess as 15Lbs DA pull, it's pretty stiff and not quite as smooth as I would like either. I'll start moving into my new place June 3 and have access to all my tools then, so sometime after that I will be doing the action job, but my question stands about shortening my strain screw instead of replacing my Factory main spring.
 
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I trust Protocall Design. He knows more than most people on this forum.

I've swapped out and used the Wolf Mainspring but had to get the 8/32 set screw to make it work. It was a chore getting it to fire anything but Federal ammo.

Using the OEM Mainspring all I had to do was loosen the strain screw and then Loctite it with Blue Loctite. No problems.
 
McMaster has set screws with a nylon lock on them The 3/8" work well on round butt guns and the 1/2" work well on square butt guns. Round butt guns use a shorter strain screw and this exacerbates the problem of too little tension on the power rib type springs. At less than $6 for a 10 pack it's not a big investment to have both. Numbers are 95235A505 and 95235A507. This way I put the original spring and strain screw in a small zip loc bag with the gun serial number and it can be returned to stock at any time.
 
Thanks for the kind words, AzShooter. For those who don't know him, he is well versed on S&W revos, and a high level competitor.

I'm not the final word on anything, but I add my 2 cents to the pot in an effort to try to help others when there's a subject I have experience with. Anything I say is what I believe to be true, but YMMV. We are all learning along the way.

An easy way to lighten the trigger pull on a K, L, or N frame revo is to back off the strain screw till you get misfires with whatever ammo you want it to be reliable with, then dial it back up to 100% + 1/8 turn. If you get another misfire later on, add another 1/8 turn, etc. This is the lightest you can go with your ammo and know it will fire. NOT FOR DUTY OR CARRY GUNS.

Then with an assortment of rebound springs, find the lightest one that gives the type of trigger return you want. Some like a lighter spring for the lowest trigger pull weight, some want a snappy return for the fastest shooting. This addresses lighter pull weight. Smoothness, timing, etc. are additional. Many guns will be fine with just the spring work. Some will need other areas corrected.



The nylon lock setscrews are a good idea, but I have found that the nylon part is only good for a few adjustments, then is worn out. That's the reason I use the Loctite. It lasts for many adjustments, and you can always redo it if needed.
 
In my world every handgun is a potential self defense tool so I am mighty careful about lightening trigger pull. That's after many years of messing around with mainsprings, rebound springs, strain screws, etc.

If I couldn't get a gun to operate with a trigger pull I liked and still be 100% reliable, I got rid of it. Of course telling the buyer why I was selling it.

Gun must go bang every time, provided the ammo is good. All else is secondary.
 
For those looking for an aftermarket mainspring, my personal choice would be the Wilson Combat #178. Just one person's opinion, and doesn't mean there is anything wrong with the other ones. All the aftermarket mainsprings are lighter than the original S&W one, but then, that's the objective. I think the Wilson has the best geometry to give a lighter trigger pull for a given hammer tension. On the newer MIM style hammer stirrup, there may be a slight interference with the hooks on the mainspring. The back of the hooks can be filed a small amount to create some clearance if needed.

Lighter and smoother are two different attributes. Lighter feels smoother, so some people use them interchangeably, or view them as the same thing. A lighter trigger pull is normally achieved by reducing spring pressure, a smoother pull is achieved by refining the mating surface of parts that contact each other, and making the interaction of the parts more precise.
 
I shot competitively for quite a while and used a Davis modified S&W Model 67 in competition. On the street, I use either factory set ups or the action work performed by Andy Horvath.

Is there a difference? Of course! But, both give me a very smooth trigger action. The Davis IS lighter, but smooth tops light every time.

The only other action work I will accept is dry firing about 10,000 times to wear the parts together.

Kevin
 
Just as an interesting point of info... I have a 986 Pro Series 9mm revolver, that I bought in 2015 when they first came out.

It's advertised as having a Performance Center reduced power mainspring, so when I got it home, curiosity got the better of me and I removed the grips to see what a PC mainspring looked like.

Well, guess what... it looks exactly like a Wolff mainspring, rib and all.

The other thing that I immediately noticed, the strain screw from the factory was a different style from my other round butt K-Frames, but it had a familiar look... it was the longer style strain screw for a square butt frame.

On my 625-8, when I installed a Wolff reduced power mainspring, I copied what S&W did with the 986, and used a square butt strain screw... worked perfectly.

I think Wolff is doing S&W owners a disservice by not advising on their website that round butt S&W's need the longer screw.

It's an issue that appears here time and time again after someone swaps the mainspring on their round butt gun.

On square butt S&W's, I've never run into an issue substituting a Wolff spring.
 
First off, I don't know beans from apple butter about anybody's spring kit--------------except for Jerry Miculek's. His is idiot proof, and will give you exactly the trigger pull you want---no fuss, no muss, and no bother-----if/when you follow the instructions. I, of course, have absolutely no need for instructions of any type from anybody to replace a couple of springs!! And when I got finished, nothing would move-----the gun was locked up tight.

Discretion being the better part of valor, I decided to start over-----after I read and understood the directions. Here's the essence of what I learned: The D.A. trigger pull will be whatever you want it to be from 7 lbs. on up. You can most certainly go lower, but you are cautioned the gun will very likely fail to fire most brands of ammo/primers except for Federal at 7 lbs. Whether that's the case, or whether I need a better trigger pull gauge remains to be seen, but I'm at 7 lbs., don't have any Federal ammo, and my WW ammo goes bang every time----every single time. And the action is as slick as greased owl doo-doo.

The design of the mainspring is such that you can dial in any amount of force you want, do a bit of measuring and cutting of the strain screw, and that's that. If/when you decide you want (or need) more force, you get a new strain screw, and start over.

Last words: Read the instructions. If/when you decide you know more than Jerry Mickulek about all this, take a cold shower, get a new strain screw, and start over.

Ralph Tremaine
 
It all has to do with the alignment of the stars.

I have a new hammer kit coming soon and it has two strain screws for the difference between round and square butts. They recommend a stock mainspring to get the best results with the kit.

I ordered two from Brownell;s. One I'm leaving stock and will just use the strain screw to get a 7 pound DA pull out of my 617. I'm hoping that that weight will pop off all the rounds I intend to use in my gun.

The second spring I intend to bend slightly which will give me the desired weight.

With both setups I intend to use BLUE LOCTITE to keep the screw from moving. The kit I'm getting is call the REVUP Action Hammer Kit if anyone is interested. Trigger pull is going to be different. It will get lighter as you pull through and that should add to accuracy and speed.
 
The only thing I can tell you about Miculek's mainspring is it has a decided bend forward about 3/8" aft of the hammer stirrup. Some of you may very well understand the whys and wherefores of that, I don't. I do know that if/when you install it, as I did the first time around without bothering with the instructions, it (the upper portion of the mainspring) is well and truly jammed against the bottom of the hammer------and NOTHING moves.

After you read and follow the instructions, and as if by magic, everything fits and works just fine.

Wonders will never cease!!

Ralph Tremaine
 
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