View Full Version : Fail to fire on S&W 686

December 11, 2004, 09:50 PM
I bought a S&W 686 revolver a few years back and had the shop put in a spring kit of some sort to lighten up the trigger pull so my wife would be more comfortable with it. The gun was purchased as our primary home defense weapon at the time. The trigger pull is great in double action mode, but recently it's been having a lot of failures to detonate primers. Seems like it will always set 'em off in single action mode though. I'm guessing that a spring has just lightened up over time. Being that I don't live in the same city where I bought the gun anymore and that the going rate for a gunsmith to look at it ain't cheap around here, can anybody suggest which spring needs adjusting or replacement? Would that be the big main spring running up through the grip? Is this something fixable by someone who's largely mechanically incompetent (yeah, I can work a screwdriver :)) or should I break down and have a professional take a look?

December 11, 2004, 10:49 PM
Get a stock mainspring for it. If you can operate a screwdriver you can change the mainspring.

4V50 Gary
December 11, 2004, 11:42 PM
And that's why I hate non-factory replacement springs. There's no guarentee that they'll perform. The standards for self defense guns should be the same as for police guns - they must work 100% of the time.

Some aftermarket things are OK like sights but critical parts like springs or other internal parts should be highly scrutinized, properly installed and then thoroughly tested with the ammo that it'll be used. That's why most cop guns don't have anything other than non-factory sights (& this is only if night sights are needed). Even rubber grips can cause trouble. On modern semi-automatic pistols, the grips help to hold some springs in place. If the grip isn't properly made, the springs can walk and then something on the gun won't work.

The most you can do is to file the retention screw down a mite, but you should never replace the spring. Even the rebound lever spring can be cut one coil, but it should be tested, tested, tested for reliability in the DA mode.

Sir William
December 12, 2004, 02:56 AM
First, try a different brand of ammunition. Second, tighten the mainspring screw in the front of the frame. If that doesn't help, take it to a gunsmith. It wouldn't harm anything to spray flush the action with brake parts cleaner. Remove the grips and drown it. Ventilation and eye protection required.

Uwe Jeffries
December 12, 2004, 06:53 AM
I´ve drilled a small hole trough my grips so I could reach the main spring which runs through the main grip.This will enable you to reach the screw with a thin screwdriver. Take some loctite ( the red one,medium strength) and secure the screw. With a hairdryer you can loosen it again.
Good luck.

December 12, 2004, 09:34 AM
I don't believe this is an ammo issue. It happens with pretty much everything. You can look at the primers and tell they're getting hit lightly. So...the little screw at the front of the grip - tightening should increase main spring tension and loosening should decrease it? I believe mine is tightened all the way down. Sounds like I need to replace that spring then. Is it possible that the sear spring needs to be replaced? I'm wondering about why it seems to fire 100% when the hammer is manually cocked. Does that tension the main spring a bit more than what happens during a double action trigger pull? The scary thing is that in single action mode it literally has a hair trigger. :eek:

4V50 Gary
December 12, 2004, 12:03 PM
Sear spring (spring behind the sear) has nothing to do with speed or energy of hammer fall. It merely props the sear back into its position of rest after the trigger slips past it on its return to its (trigger) position of rest.

Replace the mainspring with your factory spring. If you must, you can file a tad bit off the mainspring screw (the one in the front of the grip). Better yet, cut (no more than) one coil off the rebound slide spring (that's what gives you the trigger tension). If the rebound slide spring is a newer one, you'll have to use (the dreaded) Dremel with a cut-off blade. Can't cut the newer ones with pliers like you could the old ones.

BTW, I'd rather tackle the rebound slide spring approach rather than remove metal off the main spring screw.

Lazy D
December 12, 2004, 07:07 PM
I have done hundreds of trigger jobs on S&W Revolvers. To test the amount of energy striking the primer, take an old cleaning rod (Aluminum) that will fit easily down the bore. Cut it down and weigh it on a powder scale. You need to get it to 270 grains. It should be about 5-6 inches long, depending on diameter. Cock the hammer and drop the rod down the bore. With the muzzle pointed straight up dry fire the gun. The strike should propel the rod at least 12" up above the muzzle. If it doesn't it will not reliable detonate primers. A longer strain screw will help or as others have suggested replace the factory spring. If you try to fit a new screw, be very careful when filling it down. Take one stroke at a time and test it.

If it has plenty of power you need to start looking at something else. Other possible problems are "cylinder end shake" With the cylinder closed does the cylinder have any play fore and aft. If there is any play in it the primer may just be too far away from the firing pin. Now you start getting into a little more specialized fix. The fix for it is to stretch the yoke. It does take very specific tools to do this.

These are the two most common problems, as long as you don't have a damaged fireing pin or hammer nose

Good Luck

4V50 Gary
December 12, 2004, 11:34 PM
Hey, nifty test. Never learned that in Armorer's school. Guess that'll work for any caliber since primers are primers are primers. (OK, they're not all the same and we should test all types of primers). In school we knew enough to use Speer plastic cases (primers only) without the black plastic bullet. Mind you, testing wasn't done at the school.

k in AR
December 13, 2004, 03:24 PM
Classic "tune up" failure to fire... no problem... until your life requires it to go bang!
I'm not going to restate all that has been said about the springs, and very well said guys, but I didn't notice anyone to suggest the "gun doctor" <L> could have possible filed off the straine screw. I.e. it still bottoms out, but isn't proper tension on the hammer spring. I've seen this before and it will make you scratch your head until you measure it.
BTW, Wolff springs are fine. But, if the gun is for "defense use", use full power (standard) springs, the reduced power are for target shooters. Return springs are a good trigger reducer also, but once again if it is for self defense use the factory standard and learn to shoot the gun.
Remember, paper don't shoot back, live perps do.

December 13, 2004, 03:42 PM
This is one of those "live and learn the hard way" sort of things. I bought the gun about 6 years ago, primarily for home defense. I wanted my wife to be able to shoot it comfortably. The dealer suggested dropping in a trigger kit. I'm ashamed to say that I don't know what was done specifically, but I believe it was just some lighter springs. For years, it functioned without a hiccup, but I guess the spring's worn out some now. I'm older and wiser now and wouldn't do something like this again, at least not for a defense weapon. I agree with ya'll 100% and I'm just wanting to get it back the way it should be from the factory. I'm hoping that just means replacing the main spring that runs up through the grip. The screw that hits it from the front of the grip doesn't appear to have been modified, but it is screwed all the way in.

Lazy D
December 13, 2004, 07:29 PM
Hey Mike, All strain screw are altered. The factory new screws come extra long to allow some fitting. If you don't have access to a new one I have many. You will need the test rod (270 grains) and a file. CAUTION: when you put in a new strain screw and dry fire with the test rod, it will put that sucker in orbit. :p
E-mail me your address if you need one and i'll shoot you one in the mail.

Good luck.

December 17, 2004, 07:10 PM
I had a problem like that on DA with a Smith 625. Upon disassembly, I found the former owner had messed with the main spring and the strain screw. After a thorough cleaning and lube, buy a factory standard main spring and a new strain screw, install, and I bet the problem goes away. The DA trigger pull will be a bit stiff for awhile. However, use snap caps (A-Zoom are the best IMHO) and do DA dry firing about a thousand times. Your ammo will definitely go bang!