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Firing Pin Question

May 15 2017 at 8:33 AM
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Andrew  (Login spEKTre)

 
Guys I have this really nice model 10-5 Smith and it has this issue with "Clickers" ( light strikes ), I removed a primer hammer loaded it into a shell and dry fired it and found that the strike was not concentric. Initially I just thought it was out of time but after checking the timing using the drag on the cylinder technique all cylinders time perfectly, the issue is that the strikes are low. A digital photo showed that it was low and not left or right of centre.

My question is this, the firing pin is on the hammer and I am wondering if its possible the spring behind it is too strong and is forcing it lower on the primer than it should be ? any advice would be appreciated immensely.

 
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Unregistered Member
(Login tonyk1960)

Firing pin question

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May 15 2017, 6:04 PM 

Andrew, how low is low? None of mine strike in the centre of the primer and I know of very few that do. I suppose the next question would be how much do you have the mainspring turned back. Do they light strike on fast runs or just slow runs around the stick.

All things considering unless the firing pin is striking the edge of the pocket it "should" cause the primer to go off if you have enough inertia on the hammer. Have you bobbed the hammer? Light hammer means more speed required to set primers off, which equates to winding that mainspring up.

If all else fails then it's a trip to see Max.

cheers

 
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Andrew
(Login spEKTre)

Re: Firing pin question

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May 15 2017, 8:23 PM 

Tony the strikes are only slightly off centre and the interesting thing is no matter how many times you hit the one that doesn't go off it will never strike, eject it and rotate and bang off it goes. I am wondering if its more a reloading issue now, every now and then I have a primer that doesn't go in smoothly so I will mark those and see if its a correlation. The do light strike on all and any stage of service slow or quick. The hammer is bobbed and it does have a wolff in it so the odds are stacked up against it.

I was more curious about the firing pin fixed on the hammer and whether a heavier spring would force the pin lower on the primer. Max is super busy ( always is ) and turn around times are 3+ months for smaller jobs like this so for the interim I will wind that strain screw up sad.gif

 
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Tony Kent
(Login tonyk1960)

Firing pin question

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May 16 2017, 3:36 AM 

Andrew, you answered a couple of other questions I had at the back of my mind. I have had the same issue with re-striking the same case still in the gun, and you are right, no matter how many times you hit it, it still won't go off....but turn it 90 degrees and it does. I can't explain it either, just does. I have the same issue with primers, just seem to catch as they go in, but they seem to go off. There seems to be no rhyme or reason why the light strikes happen, I had PK take a look at mine (mid competition last year) and he tells me that it looks like my hammer is falling off the sear at an angle, so falling early (so another theory).

I think I can force mine to light strike by not pulling back straight through, just one of my theories to make me squeeze that trigger. My hammer still has the spur and the original spring in it, it really doesn't matter if it is heavy, just has to be smooth. I have a little Mod 10 with no sights and a 4 inch barrel, totally stock standard but can shoot 480 with it in WA480.

Wind the spring up, look at those sights, squeeze that trigger and most of all....believe. I don't think it has anything to do with the firing pin spring, unless someone here can convince us otherwise.


You think 3+ months is bad, I won't tell you how long PK's list is. The big Q dropped my gunbox going up to Cairns last year and bent my Aristocrat, PK took it home and fixed it that arvo. When I asked him about building a gun for me as I already had one in the safe ready to go, he told me to leave it with him and see him next year to see how it's going wink.gif.... it's still in the safe.

 
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JB
(Login x-cop)

Firing pin question

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May 16 2017, 10:22 AM 

Just curious, everyone here has been talking about getting the light hits or misfires and then going around and still getting a misfire, thinking possibility of off center hits or light spring(Wolff). What primers are we talking about? Rotating the shell around 90 degrees and getting it to fire tell me the priming component not consistent in primer possibly, or primer not seated and bottomed out good, or inconsistent in bottom of pocket. Crushing a primer when seating.Some hand seat the primers because they get the feel better for consistent seat.
Dont forget to check end shake in yoke and cylinder. Sooner or later it will open up after lot of shooting. Short hammer fall(falls just at time it locks up) can cause misfires if action has been worked on. Most of time strain screw backed out too far for that lighter pull. Just some "other" thoughts. Still cant get Federal small pistol primers here.

 
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JPE
(Login JPE0392)

Re: Firing pin question

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May 17 2017, 12:01 AM 

Ok lets talk S&W revolvers. A low firing pin strike on primer has nothing to do with the firing pin spring as a lot of S&W Models don't even have a spring a all. Possible causes? Has the hammer nose bushing been checked for alignment? Has the cylinder been checked for proper alignment to the frame (slash)firing pin hole? The firing pin spring only keeps the firing pin from flying up when hammer falls and contacting top of frame and slowing down hammer as it contacts primer. The hammer nose bushing directs the hammer nose (firing pin)to the primer. A professionally done trigger job consists of no less than 50 checks, adjustments, and refitting of internal parts. It takes anywhere from 3 to 5 hours, sometimes much more to make a trigger operate as a Champion shooter requires it to work. A trigger job does not come out of a bag and include two lighter springs. A strain screw was never meant to be adjusted, it is meant to be screwed down tight and never loosened except to remove for a total cleaning. The main spring on any S&W Revolver (except j frames)needs to provide a minimum hammer fall of 3 LBS. for Federal match primers and at least 3.5 LBS. for any other Primers. If you are changing the tension of the strain screw you are changing the geometry of the main spring resulting in inconsistent ignition (miss fires).The strain screw was never intended to be a means of lightening the trigger pull weight.Many things cause misfires. End shake, hammer nose protrusion, unseated primers, hard primers, hammer contacting frame or side plate, timing ,ranging etc. just to name a few . I assure you Philip Hemphill ,Robert Vadeaz and any other Champion shooter does not get their trigger job out of a bag and expect that alone to produce Championship results. JPE

 
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Andrew
(Login spEKTre)

Re: Firing pin question

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May 22 2017, 6:06 PM 

JPE
This is some awesome detail that I'm sure shooters for years to come will read and be well informed. You were spot on with the alignment of the firing pin through the firing pin bushing as even with my dodgy eyes I can see the firing pin comes through at differing depths at every strike of the hammer thanks.

Now I have to ask you how to fix it ?

 
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Unregistered Member
(Login JPE0392)

Re: Firing pin question

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May 23 2017, 1:37 AM 

Andrew the Hammer nose bushing may be slightly loose and rotating just a little causing the hammer nose protrusion to change with each drop of the hammer as it contacts the bushing prior to entering the bushing. If that is the situation the fix is to install and stake in a new bushing and the hammer nose should be changed as well as it may be fractured causing the tip to fall off at the most inopportune moment. Another possibility is the hammer is not falling straight into the frame(off to one side)causing the hammer nose to hit the bushing rather than the bushing guiding it to the primer. In this case the sear refit or replacement should help. Other possible caused may be a worn hammer pivot pin or an oversize hole in the hammer where it pivots on the pin. This constant contact can loosen the bushing and even turn it slightly. In extreme cases the bushing can be knocked out of the frame (rare but happens). With an empty gun drop the hammer a few times and check to see if the bushing protrudes beyond the recoil shield if it does the bushing is loose.it must be dead flat with the recoil shield. Good luck ! JPE

 
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Andrew
(Login spEKTre)

Re: Firing pin question

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June 19 2017, 4:06 AM 

Solved the issue, eventually got around to pulling the revolver apart yesterday, soon as I took the hammer out I saw the problem. The gun builder put a 1 and 1/2 thou shim on the inside which was pushing the hammer into the bushing, removed it and bingo 50 shots without a misfire.

 
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JPE
(Login JPE0392)

FIRING PIN QUESTION

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June 19 2017, 6:29 PM 

Andrew that was going to be my next post. ( NO REALLY) LOL! Yea sometimes it's something that simple. JP

 
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