My little 15-2 has a problem where the main spring contacts the rebound slide just before it locks into the SA position.
The spring is essentially flat until the last quarter inch or so.
I'm considering a more modern spring with an arc to it. That would route the spring away from the rebound slide and give me the chance to lighten the pull a bit.
My concern is light primer strikes. I have thousands of CCI primers that will be used in this gun.
Which spring would you folks suggest?

Sounds like a short or backed out strain screw to me. The hammer springs are pretty flat when removed from the gun, and a proper length strain screw run all the way in puts some arc into them. The strain screw should never be used to adjust trigger pull. Lighter main springs and rebound springs are available for that. I have found over the last 50 or so years that the rebound spring has the most effect on trigger pull, both double and single action.

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Tom
1560

Skeetr57 is absolutely correct. The problem is with the strain screw, not the spring. Either it has been loosened or shortened. If loose, tighten it. If it is tight then it needs to be replaced with a new one that can be fit properly. It is the strain screw that puts the arch in the spring as it loads the spring.

Since you obviously do not understand the relationship of parts, or the mechanics of a S&W revolver, I would strongly recommend having the strain screw fit by someone who does. Even if you have to send it back to S&W for the work it will be money well spent.

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Gunsmithing since 1961

Use the factory main spring and tighten the strain screw right down. It should not be backed out at all. Some people shorten them to ease the trigger pull even when the strain screw is tightened all the way down. If shortened, order a new one from S&W.

let me start out by saying that I have a very good understanding of the parts inside the guns and how they work together.
The strain screw has not been shortened as far as I can tell. It was screwed all the way in.
I do not like having the strain screw in any other position.

The spring is essentially flat as stated above but it's got a little S shape towards the end (well before the hooks) as if a previous owner was playing with it. It doesn't match the photos I've seen or other main springs out of the guns. With all the screwdriver scarring on the screws it's pretty obvious that someone violated this gun repeatedly over the last 50 years. I've owned it a whopping two weeks.

My 25-2 had an arched spring in it when I brought it home. I've read a bit here and there about some newer aftermarket springs having this arc and being able to provide ample impact for hard primers without being excessively heavy. I slid it into the 15-2 and it gave me the results I'd like. However, this spring has no manufacturers markings.

I've been through the guts of the 15 and went over every working surface in great detail. It's a beautiful trigger with the 25's spring and one of the heaviest I've handled with it's current spring.

I plan on replacing both the rebound spring as well as the main spring. That main spring concerns me more because of the possibility of light strikes. The Wolff springs have a more pronounced "power bar" running down the middle and less of an arc than the current spring in the 25. Again, with it being a used gun I have no idea which spring is in it.
Is the Wolff kit the way to go or should I look at other manufacturers?

If the "original" spring in your gun appears malformed, it almost certainly has been monkeyed. If it's contacting the rebound slide just before cocking, that explains the heavy pull: you're having to lift the mainspring with the rebound slide in order to fire. Replace it with a standard S&W mainspring and you should be well satisfied.

Larry

Here's a picture of a 67, which should be about the same, for reference. Hope it helps some with your mystery. (Ignore all the notes in the picture. I was trying to help out a friend over long distance.)

Years ago, the "gunsmith" wanabees would put a kink in the upper 1/3 of the mainspring to lessen the trigger pull as part of a trigger job for bullseye shooting. Sounds like this has been done here. I'd replace with a factory stock mainspring.

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H Richard
SWCA1967 SWHF244

Feets,

Before reading any further go to the bottom and read my sig line. This is fact, I have worked on literally thousands of S&W revolvers over the past 50+ years, I do know what I am talking about.

Let's take your points one by one.

I am sorry if you think I am beating up on you. I have years of experience and am trying to help you. When all you want to do is argue and be defensive it is particularly annoying. I have never understood why anyone would start with "I have a problem which I don't understand," as you have, and when help is given then you start arguing as though you already knew the answer! If you did, then why did you ask the question?

FWIW, all S&W K, L, and N Frame factory mainsprings are identical.

With that said, I am finished, in more ways than one.

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Gunsmithing since 1961

Feets, I can't get past your first sentence. You say your main spring is contacting the rebound slide? That doesn't register. Perhaps you're not totally used to the nominclature. Those two parts do not come even close to one another. I don't want to sound like a know-it-all, because we're all students. Get a copy of Kuhnhausen's book. You'll love it. Good luck.

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Why, I aughta.....

Mike, when pulling the hammer back the spring would contact the rebound slide just before locking into place. That last little half a millimeter of movement took much more effort than the rest of the pull. I removed the grips and saw the contact.

Alk, I appreciate your input. I'd like to replace all five screws due to the mauling they've taken over the last 50 years. It's a sad day when I have to tap the proper sized screwdriver into the slot.
I see that Numrich, Brownells, and Midway are all out of the nickel crowned yoke and strain screws.
Does S&W still service these parts? If not, what's a good source?
I have a local gunsmith who has all kinds of crazy stuff for prehistoric guns (he was working on a pinfire gun last time I was in there) but I really don't like bothering him for piddly stuff. It's also tough for me to get to his shop since he's only open 3 days a week.

feets,

Screws are usually available from S&W, Brownells, Midway, Jack First and, if necessary, Numrich, AKA E-Gun Parts.

If you take the sideplate off and watch closely you will see that the hooks of the mainspring are stubbing against the bottom of the hammer in the area that is circled in yellow in 5-Shot's photo. This may be what you believe is the rebound slide striking the spring, and why it gets very hard to cock the gun that last 1/4" or so. This is caused by the spring not having enough arch, it lengthens when the strain screw is either loosened or shortened. When the strain screw is replaced this will take care of itself.

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Gunsmithing since 1961

No. It was in contact with the rebound slide.
When the hammer is pulled back the trigger moves rearward and pushes the rebound slide back as well. Just before the hammer locked in place the spring made contact with the top corner of the rebound slide. The hammer then had to pull the spring over the slide for the last little bit of movement necessary.
I didn't notice it when firing double action because the hammer doesn't move as far rearward.

I'll check with S&W to see if they have the correct screws for my little plinker.

A bit late to the party, but I just now tried to fit a "factory strength" Wolff mainspring into a new 686, and it also hit the rebound slide on single action.
Yes, the strain screw is all the way in, and yes, it does hit the back of the rebound slide on the upper corner. This was a new gun and the strain screw has not been touched. Nor has either spring been bent in any way. A double action stroke is fine with the Wolff spring, just barely clearing the upper corner of the rebound slide, but pulling the hammer back in single action results in contact before the hammer reaches full cock. It is enough contact that you can see it pushing the rear of the rebound slide down against the frame.
I put the factory mainspring back in and it works fine - it does not come anywhere near the rebound slide. I swapped both of them out three times just to make sure I was getting the spring seated correctly, same results every time.
The Wolff spring has a different bend point than the factory spring, and it apparently needs a slightly longer than normal strain screw in this particular gun. Or Wolff has screwed up on this run of springs.
Anyway, I'm staying with the factory spring for now. The Wolff is a bit smoother in double action, but I want a good single action stroke too.

.One more thing that Bubba the backyard gunsmith does is to cut the rebound slide spring to lighten the trigger pull. This allows the spring to travel back further. If you're looking for a lighter trigger pull buy a Wolf spring kit. They give you 3 rebound slide springs and a new main spring or buy new factory springs, you'll need them with CCI primers!
jcelect SWCA#LM723

I think you'll find that the Wolff mainspring is stamped (hence the "power rib"), while the factory spring is forged and machined. That alone signals a quality issue for me that causes me to avoid the Wolff. Their coil springs may be just fine, but I've never had enough of an issue with factory springs to consider them.

Just my $.02 worth
Larry

I gotta stick up for feets here. I didn't read his reply as argumentative or defensive.- he was only further addressing the problem. I do have to say that if you had aimed "since you obviously don't understand the relationship of parts, or the mechanics of a S&W revolver...." at me, I would have been more than a little defensive my own self. I'm sure that could have been worded in a more friendly way.

you spring is in backwards....if it comes close to the rebound slide

If the spring was in backwards the hooks that engage the hammer swivel would be in the wrong direction and that wouldn't work at all.

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H Richard
SWCA1967 SWHF244

well that's why it doesn't work right....the only way the flat spring can contact the rebound slide is if it is in backwards

Tony. Seriously. The mainspring will only fit one way. It will not go in backwards or upside down or in any way other than the one way it is designed to go. Take one out and see for yourself.

This is a real puzzler so I'm grasping at straws. In the photo above, take a look at the link between the spring and the hammer. When the hammer is cocked is that link free to swing up to where it needs to go or is it being forced to push down some. The only reason I bring this up is I installed this link upside down in a much newer model (admittedly an entirely different arrangement) and its movement was limited as a result. The gun acted just like yours. I don't think yours is can be installed wrong but debris could be blocking it's movement.

Ed

I agree the solution is . . . in order of importance . . . to (1) replace the strain screw and fit it so the hammer spring is properly arched, (2) replace the main spring to insure you start with the proper spring tension and arc, and (3) replace the rebound spring to insure it is full-length to properly regulate the rebound slide travel.

Here is a pre-war M&P with what I understand is the exact same problem as the OP describes. Pictures 1 and 2 are with the strain screw (fully tightened) that is too short. And yes, it is possible for the upper corner of the rebound slide to contact the main spring if the strain screw is so short that the main spring has no arch.






In pictures 3 and 4 below, I've added a shim (happens to be another hammer spring) to correct the arch. It makes a whole lot of difference.






The example above happens to be a pre-war strain screw but I have more than a dozen of the post-war variety to fit the OP's 15-2. If you'll send me a PM with your mailing address, I'll put one in the mail.




Russ

Hi:
Consider installing a new mainspring and mainspring tension screw.
If you are not the original owner of this revolver, it is possible that a previous owner did shorten the mainspring screw "A Mite" and bent the mainspring also to lighten the action.

I agree an altered spring or screw will cause this problem. The problem with mine was solely with the Wolff mainspring. Maybe that was what was in the gun that originally started this thread ?
Consider this - you go in a tackle store, you can choose a fishing rod that bends at the tip, a rod that bends 1/3 of the way down, one that bends in the middle, or a panfish rod that bends like a wet noodle all the way to the handle.
I suspect aftermarket mainsprings are really no different - they design them to have different bend rates for a 'smoother double action pull, or whatever, and they simply bend differently from a factory spring. If they didn't behave differently, there would be no point in making them and they would put themselves out of business quickly.
The Wolff spring might be just fine in an older gun, but in my newer 686 with the MIM hammer and swing link, it bends in a way that lets it contact the rebound slide.
And I haven't measured, but the MIM swing link appears shorter to me than the older links that were pinned. Maybe not, but the geometry looks a bit different to me.

Maybe the hammer's in backward too.
(sorry, I couldn't resist!)

In case anyone might be interested, I just got an email from Wolff tech support confirming that 686's need a longer than factory strain screw with their factory strength mainspring.
It would be nice if they would warn people about that up front.
I'll just stick with the factory spring and screw.

I've seen this as well. The strain screw sets into the rib on the spring, so it doesn't put the same arc on it.

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