Need advice on mainstring for 686

[bumnote]

I recently replaced the mainspring in my 686-5 with the one from the Wolff reduced power kit. I've used the same kit on my 67-1, and liked it alot...not too stiff not too light. However in the 686-5 it's too light, way too light for my liking. I had installed the 15lb rebound slide spring as well and then reinstalled the factory rebound spring and that helped somewhat, but I still ended up installing a longer firing pin to prevent light primer strikes. I don't have a scale (now I have a reason to buy one though) but my guess is the DA pull is probably 3.5-4.5lbs...it's seriously light. The 686 has no problem w/ light strikes w/ the longer firing pin, but the bottom line is I just don't like the DA pull this light but I'd to avoid a return to the heavier pull from the the factory spring.
Is there another brand/type of mainspring that will give me a happy medium or maybe a heavier hammer would help? It's the stock hammer assembly.
Also am I correct in assuming that the reason the 67-1 w/ the older style .500 target hammer I had installed in it works well with this set-up, but the newer style hammers are lighter and that's the reason for the difference?

Any advice would be greatly appreciated.

 

[OKFC05]

Quick way to deal with it is to get a grade 8, size 8-32 cap screw and custom make a strain screw to get the pull you want. When you put in the strutted mainspring, your strain screw became too short. I'd guess you need about 1/2", but you can grind to whatever you need. Ordinary screws are too soft.

 

[bumnote]

Thanks OKC05! That's something I didn't think of...but probably should have. I'l give that a try.

 

[bountyhunter]

I recently replaced the mainspring in my 686-5 with the one from the Wolff reduced power kit. I've used the same kit on my 67-1, and liked it alot...not too stiff not too light. However in the 686-5 it's too light, way too light for my liking. I had installed the 15lb rebound slide spring as well and then reinstalled the factory rebound spring and that helped somewhat, but I still ended up installing a longer firing pin to prevent light primer strikes. I don't have a scale (now I have a reason to buy one though) but my guess is the DA pull is probably 3.5-4.5lbs...it's seriously light. The 686 has no problem w/ light strikes w/ the longer firing pin, but the bottom line is I just don't like the DA pull this light but I'd to avoid a return to the heavier pull from the the factory spring.
Is there another brand/type of mainspring that will give me a happy medium or maybe a heavier hammer would help? It's the stock hammer assembly.
Also am I correct in assuming that the reason the 67-1 w/ the older style .500 target hammer I had installed in it works well with this set-up, but the newer style hammers are lighter and that's the reason for the difference?

Any advice would be greatly appreciated.

This is the reason I no longer fork out the $$$ for aftermarket mainsprings, I just bend the stock one a bit and dial in the force to where I like it. Before you bend it, lay it sideways on a paper and trace along it so you can compare the curve later. Use three small screwdriver handles to get a gradual bend centered about 1/3 of the way up from the bottom. making it flatter = more spring force, more curve = less force.

Speaking of wasting money: unless the stock firing pin is defective, those longer ones do absolutely nothing to increase firing energy IMHO. The firing pin is stopped by the primer anyway and the stock ones are plenty long enough to do the job. I did take data by progressively reducing mainspring force using both long/short pins and there was no difference.

I seriously doubt you have a 4# DA pull that can still ignite most primers. If you did that, I would sure like to know the secret. A Wolf reduced power mainspring and rebound spring (and stock strain screw) will typically give a DA pull in the 7 - 8# ballpark. It is true the "ribbed" mainsprings will "cone" the head of the stock strain screw and reduce it's effective length pretty rapidly because the screw tips will mushroom.

 

[Wayne M]

Good advice, bountyhunter. I've bent a lot of mainsprings and cut a lot of rebound slide springs in the last 40 years and always got just what I wanted.

 

[bountyhunter]

Good advice, bountyhunter. I've bent a lot of mainsprings and cut a lot of rebound slide springs in the last 40 years and always got just what I wanted.

Yeah, but it seems us spring fiddlers are not politically stylish these days. Most of the time I admit to bending or clipping, I get a lot of nay sayers.... it's just a pain to stock a mess of different rebound springs when you can just snip the stock one. And the thing that amazes me is the people who laugh at me for bending mainsprings will suggest filing the heads on strain screws to reduce spring force.... which works until the head flattens a bit and the light strike misfires start. At least if I bend a mainspring, I can always bend it back for more pop.

 

[andyo5]

I have tried both the Wolfe mainspring and bending the claw of the original mainspring methods. The Wolfe was always too light to be reliable, and I had to add a shim to the tip of the strain screw to get it to work.
Nowadays I do what the factory does. I leave the factory mainspring alone and adjust the length of the strain screw to get the feel that I want.
With the strain screw fully turned in, back it out in 1/2 turn increments and test it for reliability in single action (the worst case). When you get to the point that it is no longer reliable, turn it back in by 1/4 turn and test again. Continue until it is reliable again. Be sure to keep track of how many turns you are from fully seated. Now you have reached the limit of length that you can remove from the screw.
Now remove the screw and measure with a caliper the distance between threads. Each thread represents one full turn of the screw. So for example if thread distance is 0.020" and you ended up at 1 1/2 turns from fully seated, then you can safely remove 0.030" of metal from the tip of the screw. (To allow for variation in measurement and the "murphy" factor, I would remove less than this...perhaps 1/4 turn less).
Look at the tip of the screw as it came from the factory. The edges have been bevelled to assure that the center of the screw contacts the mainspring instead of the edges. You should finish your job by doing the same thing.

 

[KLNFrame]

Is there another brand/type of mainspring that will give me a happy medium or maybe a heavier hammer would help? It's the stock hammer assembly.
Any advice would be greatly appreciated.

Try Jerry Miculek ( Bang Corp ) Springs.I don't use anything else.

Peter

 

[bountyhunter]

I don't grind the tips of strain screws because: they are kind of pricey, a pain to order because the different models use different screws, and most important: once the metal is gone, it's gone forever and the tips shorten themselves over time as the screw end flattens off and mushrooms out. Then the misfires start and you have to replace the screw or put in a shim.

If you want to effectively shorten the screw, an easy way is to use blue loctite and just back it out a shade. I have never had a screw walk using blue loctite. However, bending the spring a touch is easy too if you want to run the screw fully turned down and still reduce DA pull.

 

[bountyhunter]

I have tried both the Wolfe mainspring and bending the claw of the original mainspring methods. The Wolfe was always too light to be reliable, and I had to add a shim to the tip of the strain screw to get it to work.

The Wolf ribbed springs generally will give good ignition if used with a new strain screw. The problem is the "rib" (groove) will pretty quickly cone the head of the strain screw letting the screw go farther in, effectively reducing it's length and giving misfires. I often wondered why Wolf didn't press a "flat" in the spring where the strain screw engages it to reduce this problem.

 

[bountyhunter]

I leave the factory mainspring alone and adjust the length of the strain screw to get the feel that I want.
With the strain screw fully turned in, back it out in 1/2 turn increments and test it for reliability in single action (the worst case).

Actually, single action is not the worst case for ignition it's the easiest for the gun to fire. The hammer goes back farther in SA cocking mode so you get more pop in SA. A DA pull is worst case mode and generally after the gun is hot so the metal is warmed up. If you are tweaking springs, make sure to fire DA to test.

 

[tomcatt51]

The other thing is that when you back off the strain screw the installed mainspring becomes longer. Back the strain screw off enough and it will bind the hammer link/stirrup against the hammer. Even if it's not binding it messes up the link/hammer relationship/geometry. Bending the spring "fixes" that issue. A reduced Wolffe or Bang or Wilson kit avoids that with a more arched spring. Wolffe mainsprings come stock in some S&W revolvers. There's a S&W part # for it.

 

[Wayne M]

Yeah, but it seems us spring fiddlers are not politically stylish these days. Most of the time I admit to bending or clipping, I get a lot of nay sayers.... it's just a pain to stock a mess of different rebound springs when you can just snip the stock one. And the thing that amazes me is the people who laugh at me for bending mainsprings will suggest filing the heads on strain screws to reduce spring force.... which works until the head flattens a bit and the light strike misfires start. At least if I bend a mainspring, I can always bend it back for more pop.

When I hear from the pros that bending doesn't work(for whatever reason) I just say: "Did I say I did that? I meant to say I heard about it somewhere. If it doesn't work I'm sure not gonna try it!"

 

[bountyhunter]

When I hear from the pros that bending doesn't work(for whatever reason) I just say: "Did I say I did that? I meant to say I heard about it somewhere. If it doesn't work I'm sure not gonna try it!"

I would probably say something like: "I'm glad you didn't tell me it wouldn't work before, because I might not have done it...."

 

[S&W revolverman]

Quick way to deal with it is to get a grade 8, size 8-32 cap screw and custom make a strain screw to get the pull you want. When you put in the strutted mainspring, your strain screw became too short. I'd guess you need about 1/2", but you can grind to whatever you need. Ordinary screws are too soft.

Where would one purchase grade 8, size 8-32 cap screws?

chris

 

[tomcatt51]

Where would one purchase grade 8, size 8-32 cap screws?

chris

What you want is an 8-32 socket set screw. It's a common thread. My local Tru-Value Hardware has them. 1/2" or 3/8" long depending on your frame. Notch the head so you can repeat how far it's screwed in and secure it with 290 (wicking) Loctite.

 

[Black_Talon]

Where would one purchase grade 8, size 8-32 cap screws?

chris

McMaster-Carr

 

[S&W revolverman]

tomcatt51 and Black Talon - thanks for the useful info.

chris