686-6 Competitor firing pin problems - Missing fire

[Andreifus]

Hi all,

I'm experiencing something bad (missing fire) with my new baby (800 shots fired until today), only when I fire in double action mode (no problem in single action instead, because the shoot seems to be stronger).

You can se the problem in the picture attached.....
Sometimes, completlely randomly, it happens that the primer is not hit in the right way (too weakly).

This happens 5,6 times each 100 shoot (there is not a rule) I've also just verified the screw in the gun handle but it's screwed at maximum....
This happens either with refilled cartridges than commercial ones I use CCI smal pistol primers (500) for my reloaded cartridges

The gun is really "young" , so I don't think the firing pin is damaged or consumed. The problem occurred from the beginning.

Do you have any idea what could be causing this annoying problem?
Thanks a lot for your help....

Andrea

 

[Milton]

Check the tightness of your strain screw.

 

[series guy]

I have found a few round butt models using the power rib main spring from the factory that needed a longer strain screw. You can try a spent primer cup with the anvil removed installed over the end of the strain screw for a cheap and easy fix.

 

[armorer951]

If the hammer spring and the hammer screw have been confirmed as factory and unaltered, there are a few things to check to try to diagnose the issue.........

Check the rear gauge, or headspace, the cleanliness of the cylinder assembly, and the fitness, or OAL of the firing pin.

When the gun is clean, and properly/completely assembled, and empty, check (with feeler gauges) the distance between the breechface and the rear face of the clyinder. This distance should be .060" - .068". (the closer to .060" the better)

The cylinder assembly needs to be clean for the gun to fire properly, especially the area under the extractor....and the extractor itself.

Firing pins from the factory show quite a bit of variance in terms of their length, which can affect protrusion. Check the length of the firing pin to see that it is at least .494" long. If it is short, try a new OEM factory one, or order a longer pin from Apex or Cylinder & Slide. While you are checking the pin, clean the pin and spring, and the pin cavity in the frame thoroughly. Put the clean pin and spring back in the firing pin cavity without lubrication.

 

[Protocall_Design]

The CCI primers are the hardest of all. Federal is the softest. If you can, switch to Federal or Winchester primers. They will dent easier.

Also, as you are just on the borderline of not working DA, you can take the spring out and bend it a little straighter and put it back in.

Edit to add: You can also make the original screw longer by chucking it in a drill press or cordless drill and filing material off the bottom side of the head while it's spinning. This allows the screw to go in further, in effect making it longer.

 

[BLUEDOT37]

Many good suggestions to a problem that's hard to diagnose from a distance.

I'd lean toward the strain screw's length too. As mentioned, the revolvers with the Power Rib mainsprings seem to be more prone to your symptom because of the groove in the spring.

S&W seems to have several different length strain screws. I started measuring the threaded portion of those screw whenever I do some maintenance on my revolvers & have come up with a wide range of lengths just in the percentage I've documented so far.

They've ranged from .332" to .396" long (the threaded portion), all round butt frames. The shorter lengths I've seen have been on those with a standard flat mainspring.

The longer lengths are on the Performance models with the ribbed mainspring. The longer length screw is needed, because of the ribbed springs groove, to obtain adequate force on it.

You might want to remove the screw & measure the threaded portion of it, with a caliper, & check the length. A short(er) screw maybe installed, or, possibly the point of it maybe flared/flattened, making it too short.

An empty fired primer cup under the screw can be a good quick check for length issues.

Additionally, if you have/can find an 8-32 x 1/2" set screw (without a head) it can be installed as a replacement for the factory strain screw. After adjusting & trimming it to length you can Loc-Tite it in place.

C&S makes a longer firing pin, that's .510", & I like to use for light strike/FTF issues also. (Factory firing pins range from .483" to .498")

Hopefully you can resolve it's issue quickly.

.

 

[Andreifus]

Thank you all for your very appreciated suggestions!

I'll start with a spent primer installed on the strain screw, and then changing primers to federal.

I will go ahead with a longer firing pin then, and I'll keep you aligned on results ;-)

Cheers
Andrea

 

[Protocall_Design]

If you change to Federal primers, you may not need to do anything else.

 

[Andreifus]

Hi,

while I apologize for the delay, I want to share with you all how I solved the problem.
First I found that the main spring wasn't properly set, so I disassembled it and then I put it again on site. I think that this first step has been successful, but i tried also some of the other solutions you gave me ;-)

I tried to fire (after resetting the spring) in double action mode, reloaded cartridges with:

1- Sellier & Bellot small pistol primer: OK no problem
2- Federal small pistol primer: OK no problem
3- Murom small pistoll primer: OK no problem

Anyway, not fully satisfied I also inserted a spent primer as @series_guy recommended. You find better details in the attached photos.

After this additional review, obviously all went fine again, I fired more than 500 shoot without any additional issue, no more missing fire issues!

So, I consider my "problem" solved, I really appreciate your suggestions, I like to thank you all for the valuable advices received.

All the best, thank you again
you're fantastic!

Andrea