Main spring for S&W 686

[Rex]

Where can I find a HEAVY main spring for my 686-4? I started having light primer strikes last fall. Primer brand doesn't seem to matter, strain screw is tight, new cases don't help, am careful to seat the primers all the way. The revolver is over 20 years old with a lot of rounds through it.
This is my last resort before it goes to a Smith somewhere. I bought the thing new and have never changed springs. I have changed stocks but can't see that the main spring rubs anywhere.

 

[KeithB]

I wonder if (a) there is dirt or hardened crud somewhere blocking the hammer or (b) something has peened, bent, or deformed enough to cause the same problem. Does this use a transfer bar and firing pin in frame or firing pin on hammer and a slot through the frame?

 

[Rex]

Firing pin on hammer nose.

 

[Will]

I would first try shimming your old one with a piece of cardboard between the screw and the spring.
This would tell you for sure if you had a weak spring.
Also check that the screw hasn’t backed out. Usually a half a turn can make the difference between it firing and not firing.

 

[david s]

If you want to try a newer factory mainspring I can offer up one. They dont have a reputation for losing tension but you never know. Is it possible that the new stocks are thin and pressing on the side plate against the area where the hammer pivots? Sort of putting the squeeze on?

 

[Ian]

End shake?

 

[358156 hp]

I use these main springs, and nothing else: https://www.gunsprings.com/SMITH & WESSON/K, L, & N FRAME/cID3/mID58/dID264 I have been let down by other manufacturers, but never Wolff. I was particularly disappointed with Wilson Combats 686 main spring. If you install a fresh Wolff main spring and the problem persists, it wasn't caused by the spring.

If you're comfortable with it, I recommend that you pop the sideplate off and clean & oil the inside. You don't have to disassemble the revolver any further than removing the side plate, once thats off you can spray some sort of Gun Scrubber inside to dissolve and flush out any gunk. I'm assuming that you are getting at least some dimpling on the primers since you are describing light strikes, not no strikes at all. If you don't want to remove the sideplate then try dripping some light gun oil down the front of the hammer, and along the sides of the hammer with the grips off and the gun inverted. The idea is to get oil up into the action . I'll also go ahead and say out loud that if the actual issue is in the action itself it could be caused by rust or even dried out and hardened old oil or my arch nemesis- WD40.

Ian raises a great point, is the rest of the action still nice & tight?

 

[Ian]

I just learned a cool trick last night for getting the side plate off without ruining the edges or having to pry on it at all: Remove the stocks, take out the screws, hold the revolver flat by the barrel with side plate up, and smartly rap the grip frame downward with the handle of a wooden hammer or face of a rawhide mallet. Basically knock the revolver out from under the side plate. Most of you probably knew that already but I didn't.

 

[RicinYakima]

Yep, old trick from the 1960's by Skeeter Skelton.

 

[RBHarter]

Get a tray like a plastic cake pan big and deep enough for the whole gun pull the grips and get 3 qt of Hoppes and pour it in the pan over the pistol let it soak a while ,maybe over night , and cycle the gun in the morning . Flip it over cycle it 10-15 times both sides down , hang it up let it run most of the Hoppes off outside . Use an under pressure solvent/lube and wash every hole towards the hammer slot . Dry it off seal up the cake box and let it settle out . You'll be sick at how much stuff is in the pan . Replace the Hoppes in it's bottles .

 

[Rex]

Thanks guys, I've had the side plate off and sprayed things with break parts cleaner then a light coat of rem-oil.
I found that Cylinder and Slide offers what they call "Old style main spring for duty carry". I would guess this is as stiff as I can get. If diesel didn't smell so bad I'd soak it in that a while and may anyway.
Thanks again for all the ideas.

 

[Brad]

The Wolff springs are what I would use. Never had a bad experience with them.

 

[Rex]

Found the problem...…….I think. I've fought this light primer strike since last fall. Blamed the primers, blamed dirty internals of the revolver thought about blaming my wife but knew better. It was the simplest and last thing I looked at. The strain screw was tight, always has been but the end was peened badly. You can see the knot on the end of the screw and the end is banged up.
How in the world does this happen? Granted the revolver is 20+ years old and shot a bit each day that I am home and the weather permits but I don't see how this can happen.
Put about .020 shim between screw and spring and will get a new one ordered.

 

[358156 hp]

Spent small pistol primers with the anvil removed has always been popular as a shim too.

 

[Rex]

New screw arrived this morning. WOW, what a difference! I got great service from Gun-Garage out of Arkansas.

 

[CZ93X62]

I just learned a cool trick last night for getting the side plate off without ruining the edges or having to pry on it at all: Remove the stocks, take out the screws, hold the revolver flat by the barrel with side plate up, and smartly rap the grip frame downward with the handle of a wooden hammer or face of a rawhide mallet. Basically knock the revolver out from under the side plate. Most of you probably knew that already but I didn't.

I just hold the revolver sideplate-down across my palm and give it a few whacks on the side of the butt, minus plate screws and stocks. The sideplate lands in my palm. I have the cylinder/crane assembly removed as well.