What works and how to do it? Hammer springs

[Don K.]

Want to modify stock hammer spring on N-frame to see if i can match the pull weight from Wolff or Wilson spring kits. I want to try cutting or filing one, and i want to try bending one. Anyone care to give a novice a decsription of what they have done, how they did it, and the results.

 

[pinkymingeo]

Why not just loosen the strain screw until you get what you want? Then you can modify one permanently, or locktite yours in place.

 

[tomcatt51]

Why not just loosen the strain screw until you get what you want?

Because as you back off the strain screw you lessen the arch in the mainspring making it effectively longer which screws up the hammer/link geometry and if the strain screw is backed off far enough will cause the link (and mainspring) to "bottom out" against the hammer.

 

[38-44HD45]

The "old fashioned" approach is to grind the sides of the spring, making it narrower. You'll need to be careful not to overheat it, and to take equal amounts of steel off each side. Bending, I've seen but never done on a Smith, although I've bent lots of Colt mainsprings to reduce DA pull. In my old age, I've decided that it is way too much work to grind down mainsprings, and the Wolff reduced power springs work well.

 

[2152hq]

I did grind a few with a belt grinder with good results.
Trying to do it with a hard wheel grinder is difficult. Unless you're using a perfectly flat faced/trued wheel, the finish you'll leave on the spring will be uneven and that's not what you want as it'll lead to weakness and breakage.
Hand finishing will then be needed, and you might as well do the job by hand with files and emery paper from the start (which can be done with fine results,,just takes a bit of time).

A belt grinder with a somewhat coarse grit belt(220 works good) to quickly take it down (plus it runs cooler with less chance of overheating while working it) followed up by finer grits will leave a very nice flat, smooth polished surface..

Fairly quick single passes to avoid overheating, followed by a dunking in water to assure the heat is gone will allow continual working time.

It's a difficult part to hang on to with your fingers when working on. But grinding the outside curve, & with light cuts and not cutting quite all the way down to the base, you can gently taper the length as needed. You don't want to alter the notch that anchors the spring in the frame.
I find it easiest to pull the spring towards me against the belt from the base (where I have ahold of it),, towards the hook. Guiding it with my other hand gently underneath. Very light cuts!

You want to gently grind the length on the outside curve to maintain what is often discribed as a 'buggywhip' taper. Don't take more material off of the end only.
Maintain the original taper, just reducing it's thickness by a very tiny amount.

Then you could do like 38-44HD45 sez,,and get springs from Wolff!
They make a good product. I've used alot of their springs in all kinds of firearms with no complaints.

 

[38-44HD45]

2152, are you talking about thinning the spring? I've seen that done, but never have done it, due to factors you mention, since the spring can easily fail if you leave a rough or uneven surface finish. What I described was narrowing the spring, while leaving the thickness the same. That process is easier on a belt sander, too, which I should have mentioned, but can be accomplished on a grinder. Safety glasses are a good idea, though, since a grinder can sure launch a spring if you lose your grip!

 

[OKFC05]

i want to try bending one. Anyone care to give a novice

Suggest you don't unless you are sure what you are doing. Bending a tempered spring can cause early failure, which is not my favorite thing to happen in a gun.

Especially considering quality springs cost less than 20 bucks and are easily installed and tuned.
BROWNELLS : SW-MS-222 MAINSPRING FOR S&W K,L,N FRAME REVOLVER - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools

And you're going to have to buy a new spring anyway if you start grinding on the original and ruin it--or 2 or 3...

 

[2152hq]

2152, are you talking about thinning the spring? I've seen that done, but never have done it, due to factors you mention, since the spring can easily fail if you leave a rough or uneven surface finish. What I described was narrowing the spring, while leaving the thickness the same. That process is easier on a belt sander, too, which I should have mentioned, but can be accomplished on a grinder. Safety glasses are a good idea, though, since a grinder can sure launch a spring if you lose your grip!

Yes thinning the spring it's entire length while leaving the width original was what I have always done. It can be a touchy job but if you do alot of belt polishing work it's just another job. I did alot of it for quite along time and polishing blindly on the bottom of the drum becomes second nature afterwhile but it does take some time to learn.

Safety glasses a must! around any of that machinery. I've had belts break and parts take off while polishing and none are a pleasent experience. No gloves though!,,they'll take your hands and feed them right between the belt and the drum especially on a slack belt sander if they get in the wrong position. I know that from experience and I didn't even realize it had been broken till years later.

All the lever action receivers we did were done on belts. The sides were done on slack belt polishers with the belt pressed against the metal from the back side with a felt block. The hand is in a very bad location in the machine! I'm sure it was...'Not OSHA approved'..

Narrowing the width on the mainspring can be done quickly and nicely on a belt too. I've just never done it that way. I've felt that the narrow width and full thickness is somehow weaker than the other way. I probably can be proved wrong by someone with a degree!!.
I've seen more than a few done that way and they were all still in one piece! Which ever works and gets the necessary results without damaging any other parts or the mechanism .

 

[Don K.]

Thanks for all of the info and advice gentlemen. Thinning, narrowing, and/or bending- interesting.
I actually have installed both a Wilson and a Wolff spring kit in 2 of my 3" .44s. Probably settle on a 12lb. or 13lb. rebound spring for both. I don't shoot "fast" enough to outrun the lighter rebound springs. Might even try an "11lb.-er". Purely subjective but the Wolff feels better to me than the Wilson (although it surely does sound "clinky")
I narrowed one stock spring using files and cleaned it up on a small inflatable drum sander. Narrowed it to the point I felt was as far as i would want to go up around the "neck" area while keeping that buggy whip taper. Big improvement over stock pull, heavier than the aftermarket springs, but still felt nice.
I cold bent another stock hammer spring using the screw and boss from my bench vise-slowly- with gloves and safety glasses! Put a nice smooth bend in the spring-better than I would have imagined. It gives a nice smooth pull of the same weight +/- as the aftermarket springs. I'm going to run that spring for a while and try to keep a "pull" count and see how it holds up. It feels great-I was shocked.
I have also done "trepidatious" trigger jobs on these guns with Mikulek's dvd. I'm very pleased with all of the results, and it is great fun.
As an aside, there are differing opinions about the benefits of spring rate changes, trigger jobs, ( porting, etc.) on shootabilty and shooter. I fall very heavily on the positive side of this debate. The difference between stock and smoothed up is huge in my opinion, it has had a great impact on my shooting, and the enjoyment i get out of my guns. I have gone as far as rendering my carry .44s D.A.O., (stoned off single action ledge) and that inflatable drum sander did an awsome job with bobing the hammers after cutting the horns off with a die grinder/cutoff wheel.

 

[2152hq]

A gentleman I worked with at a gunshop and an excellent pistolsmith, used to put the bend in S&W mainsprings while they were still in the frame.
I wish I could recall better at this point,, but as best as I can remember, this is what he did.
He backed off the tension screw all the way and placed a round dowel in between the front of the spring,,inbetween it and the frame. It had to be pushed into place with a bit of force as the spring starts to take up tension as it is moved down into position from the top.
Placed at the point he wanted the bend to occur, he then made the bend by actually pulling the hammer back in one quick motion.

The distance he pulled the hammer back and the exact point he placed the dowel were by experience and the whole operation would only take him a few moments.

The dowel was of lead or babbit material so as not to mar either the spring or frame. He did this with the gun in his lap,,not in a vise. The bend in the spring was a nice even curve and no damage was done to the hooks of the spring or the stirrup/hammer. Experience is good!