686 Competitor Failure to Fire, part two.

[fastbolt]

Agree with Old Fuff.

Expecting a single cause for a problem can create the potential for overlooking the actual causes (plural).

Also, some folks may mistake a symptom for being the actual underlying problem, and don't look deeply enough to diagnose actual problem(s) causing the symptom(s).

Best to let the company examine and correct it.

 

[Zaydok Allen]

Well, she came home a few hours ago. The service order says that the firing pin was replaced. I took a look and the firing pin seems to protrude from the frame further now after pulling the trigger than before.

So, it sounds like a very similar situation to what plinter described. Insufficient firing pin protrusion for one reason or another.

So what did I learn here? I learned some interesting facts about how the internals of a Smith revolver works. I also learned that guessing on an issue like this, based on what the gun is doing can be educational. The bottom line though, as Mr. Borland pointed out, is that failures to fire in double action could be caused by a host of different issues, and if it's under warranty, just send it in. I've enjoyed the conversation.

I'm hoping to put some round through the tube in the next week or so. I'll report back on how it goes. Glad she's home!

 

[MartinS]

You had another 686 all along? Compared struck primers? Compared firing pin protrusion? "Overthinking often makes for long journeys", Charlie Chan, 1937.

 

[Zaydok Allen]

I did compare struck primers and ones that fired successfully in DA out of the PC gun seemed to exhibit no difference from the other 686. The FTF's seemed like light strikes and the rounds that did not fire in DA on the PC gun did fire on second strikes. Of course I had to wait for possible hang fires, and when it was doing that 2-3 times per cylinder, it got real annoying fast.

I also looked at the firing pin protrusion on both guns prior to sending the gun in, and they looked the same.

The difference I noticed on the PC gun is that in double action the hammer on the PC gun falls noticeably earlier than on the other gun. Mr. Borland pointed out that the gun may be designed to do that so it fires more quickly, seeing as it is a competition gun. That seems reasonable given that the work order did not list any replacements of trigger or sear components. The hammer still falls earlier than on the other 686 after coming back.

This is a guess only, but it seems to me that the failure to fire is a combination of factors. The trigger action is very smooth from the factory, as expected. I assume that means extra stoning of the contact surfaces happens at the factory, like I'd expect on any PC gun. The mainspring is also bossed, which as I understand will result in a lighter pull. This is also evident when pulling the trigger. However, it seems the combination of smooth and light was resulting in a standard firing pin not making positive enough strikes in DA due to the reduced hammer travel distance. In that context, it makes sense that the only way to create a more positive strike, without totally changing the trigger pull to a more standard trigger feel (not that there's anything wrong with S&W triggers) was to install a slightly longer firing pin.

In comparing it to the other 686, it is in fact a hair longer. Of course, I haven't gotten a chance to even test it yet, so we'll see if it worked or not.

Again, the point here was to learn. Sending it in was really the intent from the beginning, and besides gas money, this has cost me nothing. The gas money wasn't even an issue; it just meant I did some shopping off my normal "go to the city" schedule.

If my thoughts on why the new firing pin corrected the issue are incorrect, someone else please chime in.

 

[MrBorland]

This is a guess only, but it seems to me that the failure to fire is a combination of factors.

Could be. And it could be that none of those factors include the stock firing pin, so putting in an extended FP might be bypassing the other issues. We'll be interested in hearing if the gun now fires reliably.

A note on extended FPs: Some are sensitive to being dry fired without snap caps, and can break. The Cylinder and Slide extended FP comes to mind. Not sure about the Apex pin. If S&W didn't indicate who's extended FP they used, it might be worth a call.

 

[Zaydok Allen]

Good idea. I do use snap caps 99% of the time, but it would be good information to have, none the less.

 

[Zaydok Allen]

Well, I took her out today and put 100 double action rounds through her. All fired as they were supposed to. Primer strikes seemed much more defined on the spent cases. It appears S&W did fix the issue. Total turn around was about 30 days.

Just thought I'd share for those who showed interest.

 

[Master Blaster]

Great thanks for the update.

 

[Taurus 617 CCW]

I have done quite a bit of revolver work in the past. It sounds to me like it is a combination of excessive drag on contacting parts and a sear that is allowing the hammer to fall too early. It would only happen in double action because the single action shelf is located at the end of the hammer travel. This gives it the extra momentum it needs to detonate the primer. S&W will make it right. They have great customer service.

 

[Zaydok Allen]

I have done quite a bit of revolver work in the past. It sounds to me like it is a combination of excessive drag on contacting parts and a sear that is allowing the hammer to fall too early. It would only happen in double action because the single action shelf is located at the end of the hammer travel. This gives it the extra momentum it needs to detonate the primer. S&W will make it right. They have great customer service.

They already fixed it. See posts 27 - 32.