686-4 light strikes

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BlueZee

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Howdy everyone. I posted a while back about a beautiful 686-4 that I had acquired. It has a very sweet trigger and came with an assortment of strain screws so I'm sure the previous owner had done work to it. Since I was getting light strikes pretty frequently I had S&W send me the factory strain screw and put that back in place. That helped a little but I'm still experiencing the problem mostly in double action. I bought a Wolff kit in both reduced and standard power and I have a quick question for the experts here. Which spring is the one that most influences the light strikes? The kits come with 3 different weight rebound springs. Is that the spring I should change to a heavier one to help eliminate double action light strikes? Or does that spring effect single action more and the mainspring is the one that effects double action? Any help or advice is greatly appreciated. Thanks.
 
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Rebound springs effect trigger pull weight and how fast it resets. The lighter the spring, the lighter the pull. Pick the one you like as long as reset is positive and quick. The mainspring will effect trigger pull weight and primer strikes. Quite possible the previous owner installed a low power spring and used Federal primers to get reliable ignition. Be sure the factory strain screw is all the way in. If you still get light strikes in double action then locate a standard weight mainspring and try it.
 
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A generic #8-32 x 1/2" set screw can be substituted for the factory strain screw. You should be able to buy one at any local hardware store for a few cents. It's a little longer than the factory strain screw, and can be trimmed to length if it interferes with your grips. Once an appropriate setting is determined it can be held in place with a little blue, or purple, Loctite.
 
Another option is to log on to Brownell's and order the S&W Factory Mainspring. Most of the time these are in stock and while Brownell's can be a bit slow in shipping orders at times it sure beats trying to order spare parts from S&W and spending/wasting time lost in the Phone Menu and on Hold. Another good source for parts is Numrich's but they seem to be spottier on availability and the way they will ship items out in separate packages for a single order still has me shaking my head.
 
Suggest resetting your 686 to factory springs and assessing from there.

As AQ noted, the mainspring affects ignition reliability, the rebound spring does not. Since you've returned to a factory strain screw, do the same and get a factory mainspring and factory rebound spring installed, too.

Odds are your light strikes will cease, you'll still have a smooth trigger pull, very slightly heavier, and consistent ignition.

If returning to factory specs doesn't solve the light strike issue, and since the new strain screw was installed the light strikes are largely relegated to double-action, and you believe the revolver to have been worked on by a previous owner, good chance the double action sear and/or it's contact point on the trigger have been over-polished in an "action job" and you're not getting enough lift on the hammer in double-action to reliably ignite.

That gets into more advanced gunsmithing and if factory springs and strain screw don't correct the issue, suggest seeking a qualified revolversmith.
 
Thank you for the advice folks. I think resetting everything back to factory specs is the most logical first step. If that eliminates the issue then I can start tinkering with springs from there. I really appreciate the help guys. And aside from the light strikes I can say that the 686-4 is one helluva revolver. Beautiful and accurate and feels great in the my hand. Its a 4 inch model and I'm already on the prowl for a 3 inch little brother for him. Thanks again.
 
I'm wondering if Smith sent you a strain screw for a round butt frame. It's a little shorter than a square butt strain screw. The -4 was the last of the square butt M686's. Since the -5 (1998) all standard production M686's have been been round butts. Maybe the parts tech inadvertently sent you the shorter strain screw for a newer M686. Just a theory.
 
One other point to consider: Are the light strikes happening with factory ammo or are you reloading? Sometimes reloaders do not fully seat primers and the first hit from the firing pin loses a lot of energy due to the primer being pushed back (fully seated) by the strike. Usually, the most sure check of that is if the same gun, shooting the same cartridge, fires on the second try. If so, it's likely the ammo, and not the gun.
 
BlueZee said:
Funny thing Kernel it is a round butt. On the box it says SB but its definitely a round butt. All numbers match so I know its the right box.
Click to expand...

If box label and gun do not match, is it possible, someone had some serious gunsmithing done, including converting to round butt, and then the owner had trouble with it, so that person sold the revolver? I wonder how and when it left the factory.
 
I've seen a lot of boxes marked "SB" that held round butt guns. That's a fairly common little mistake S&W makes from time to time. It's still possible it was converted to RB, I'm just saying I wouldn't go by the box alone.

An Apex extended firing pin won't help in this case. The -4 has the firing pin on the hammer -- old style. The Apex is for the newer frame mounted pin.

Could still be a problem with the firing pin. It's held in place with a rivet and was designed to be replaceable for a reason.
 
I bought a 649 4 years ago from a private seller. Absolutely beautiful trigger pull... and light hits on primers/misfires. My gunsmith said the previous owner had cut the mainspring. A factory mainspring solved the problem and the trigger pull was still good.

See why I don't buy used guns anymore? Sorry y'all.

Kaaskop49
Shield #5103
 
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