so my 686 misifres..smith mechanics help!

[dieselbeef]

with 357 125 gr loads it will fire any number of rds just fine and then the hammer will fall..and nothing will happen.
open the cyl and drop the rds. all of them have dimpled primers except the no fire one. sometimes it will go thru a bunch..over 30 and sometimes it will do it within 2 cyls.
I haven't ever noticed if its the same chamber or not..but I will next time I shoot it.
I bought it used...apparently someone been inside it cuz the screw under the grip has the telltale stretch marks in the groove. im assuming whoever did whatever has been done was no pro.
its a prelock gun. 4'' barrel. I always shoot the same load.
it never has any issues with snap caps. the hammer seems to fall everytime and it seems like its hitting the cap everytime.
ive cleaned and lubed it...im fixing to pull the sideplate....just to see if its anything obvious

any ideas

 

[buck460XVR]

Check the strain screw under the grips to make sure it is tight. Many kitchen table gunsmiths loosen this to reduce trigger pull and it leads to misfires. The buggered screw may be an indication of this.

 

[Driftwood Johnson]

Check the strain screw under the grips to make sure it is tight. Many kitchen table gunsmiths loosen this to reduce trigger pull and it leads to misfires. The buggered screw may be an indication of this.

+1

Before you remove the side plate, be sure the strain screw is screwed all the way in. The strain screw on a Smith and Wesson revolver is designed to be screwed in all the way. If somebody backed it out some to get a lighter trigger pull, that could easily lead to inconsistent ignition. The strain screw is the screw on the front of the metal grip frame.

The screw in this photo is the strain screw. Not a Model 686, but the strain screw has been in the same place on all S&W revolvers for over 100 years.

 

[MrBorland]

Yep - the strain screw's the first place to look. If it's screwed down fully, it's possible someone shortened it (to get the same effect as backing it out), or replaced the springs with reduced-power springs. It might also just need a good & thorough internal cleaning & lubing.

 

[dieselbeef]

yeah that was loose..like sticking out loose. ill tighten that before I go getting into it. contacted the guy I got it from today and he says its a real sweet trigger job aint it? guy I got it from told me the best trigger he ever shot in a sw. umm..yeah....so I tell him the deal and he says he never shot it so he cant vouche but it seemed to function ok for him..dry firing and snap caps I guess...
so I let it ride..my deal now....ill check that screw and pray a bit I think

 

[dieselbeef]

if I take that out of another 686 to check length nothing will happen inside right. long as I don't cock it
thanks

 

[roaddog28]

Yep - the strain screw's the first place to look. If it's screwed down fully, it's possible someone shortened it (to get the same effect as backing it out), or replaced the springs with reduced-power springs. It might also just need a good & thorough internal cleaning & lubing.

Another possible problem would be if somebody tried bending the hammer spring to get a lighter pull. This happen to me on a model 10. I replaced the hammer spring and strain screw at that fixed the problem.
Howard

 

[Driftwood Johnson]

yeah that was loose..like sticking out loose. ill tighten that before I go getting into it. contacted the guy I got it from today and he says its a real sweet trigger job aint it? guy I got it from told me the best trigger he ever shot in a sw. umm..yeah....so I tell him the deal and he says he never shot it so he cant vouche but it seemed to function ok for him..dry firing and snap caps I guess...
so I let it ride..my deal now....ill check that screw and pray a bit I think

Typical of a guy who has no idea what a trigger job is. By the way, it is possible to loosen the strain screw so much that the hammer spring binds against the frame when you cock the hammer.

You have found the problem, there is no need to remove the side plate. Just snug the screw all the way in.

If you remove the strain screw, the hammer spring will probably fall out of alignment in its slot in the frame. Do not remove the strain screw without first removing the grips, so you can see what happens as you loosen and tighten the strain screw.

Here is a view of the insides of a Model 17-3. Not much different than your 686. You can see the strain screw is completely screwed in, and you can see how much it bends the hammer spring. That is the way S&W designed them. If you take all the tension off the strain screw, the hammer spring will flop around inside the grip frame. The spring needs to be centered in the slot at the bottom of the frame for the grips to mount on properly. The way to do this is to gradually tighten the strain screw until the hammer spring binds in the slot in the frame. Then you nudge the spring to the center, so it does not protrude on either side. Then you snug the strain screw the rest of the way, making sure the spring does not shift as you torque the screw.

 

[James K]

Recommendation: When you are thinking of buying a revolver and the seller says "it has had a trigger job", hike up your skirts and take off running. You MIGHT lose a chance at getting a gun that has been worked on by a master pistol smith, but the odds are 1000 to 1 that the "trigger job" was done by the seller with a Dremel tool and a claw hammer.

Jim

 

[roaddog28]

If you remove the strain screw, the hammer spring will probably fall out of alignment in its slot in the frame. Do not remove the strain screw without first removing the grips, so you can see what happens as you loosen and tighten the strain screw.

+1 again. I would at least remove the grips and check to see if the hammer spring is align correctly. You want to see the same space from the hammer spring to frame on each side of the revolver. In my case the previous owner had bent the hammer spring and was not align properly.
One more case of someone not knowing what there doing.
Howard

 

[MrBorland]

contacted the guy I got it from today....so I tell him the deal...
so I let it ride

Yes, let it ride. If the issue was a few turns of the strain screw, it's really no biggie. No damage, and a simple 2-minute fix. Nothing to get worked up about, IMO.

 

[DaleA]

Driftwood Johnson, good explanation and really nice photos.

It's nice to see a photo of the insides. A friend once told me to go ahead and remove the side plate if I was done shooting my revolver and just wanted to look at all the internal pieces strewn around the work bench. I actually listened.

 

[dahermit]

all of them have dimpled primers except the no fire one.

If the no-fire does not have a firing pin mark, then the misfire may not be a loose strain screw. When the strain screw is loose, causing misfires, there is usually a dimple on ALL the primers, just not deep enough to fire the cartridge.

Look at the sides of the hammer...if it is rubbing on the frame, it can cause occasional misfires...with a dimple. If rub marks are found on the sides of the hammer, the hammer may be kept in the center with Hammer Shims (small stainless steel washers about .002 thick), available from Brownell's.

 

[dieselbeef]

I did not see anything out of the ordinary..after a cpl hundred rds...really..it had about 10 no dimple misfires.its as if it didn't even land on it at all...not a mark even with a magnifying glass.
I got home cleaned the crap out of it..super clean...took the grips off clean..and then put it back together. did not see anything that looked like an issue except the screw was way loose.. it wasn't out as far as the above pic but it was def 4 turns loose or so. I btm'd it out and ill shoot it again soon. if its a boner ill be pissed. ill fix it cuz its in super sweet condition.
but someones messed with it cuz the screws under the grips are boogered..

 

[Driftwood Johnson]

Howdy Again

Here is something you can try at home.

First, make sure the gun is unloaded.

Then find a pen or pencil that will drop all the way down the barrel and into the chambers. Remove the pen.

Cock the hammer, then drop the pen down the barrel. Point the gun up in the air, away from your face. Pull the trigger. The force of the hammer hitting the firing pin should be enough to boost the pen right up out of the barrel. Try this a bunch of times. If the pen shoots out of the barrel, your hammer is striking the firing pin with plenty of force. But if sometimes the pen moves a whole lot less than other times, then you have a problem.

 

[Rogervzv]

Great info and picture about the strain screw, Driftwood. Thank you. This is a very informative thread.

 

[James K]

Driftwood will get a laugh at this but I used to use what I called the "ouch factor." I swung out the cylinder, pulled back the latch and cocked the gun. Then I put my finger on the recoil shield and pulled the trigger. If I went "Ouch!", the firing pin impact was pretty good. If I went "OUCH#^&#@", it was ready for the hardest primers.

Jim

 

[DaleA]

I put my finger on the recoil shield and pulled the trigger

Hmmm...There might be more masochists out there than I thought...a friend tests 9-volt batteries by touching his tongue to the contacts...tingling means weak battery, 'ouch' means it's good.

 

[Driftwood Johnson]

Yeah, I used to use the ouch test on firing pins. Once I figured out my pen test I don't do that any more.

The patient says, "Doctor, it hurts when I do this." "Then don't do that!"

Henny Youngaman

 

[dieselbeef]

im just gonna shoot it tomorrow...more fun..but a pencil eraser side down might work in my chair....good tip..thanks