Discussion in 'Handguns: Revolvers' started by km101, Nov 15, 2017.
It isn't the firing pin per se. In single action the hammer has a greater arc which compresses the mainspring more and thus hits faster with more force than in double action which would cause the firing pin to move forward more.
I was wondering what the misfire primers look like and if, somehow, the primers are below flush, moving the goal posts as it were.
Dryfire gun and hold trigger fully to rear.
Cock hammer with thumb.
Hook a weight around the hammer (for example 3 1/2 LB minimum weight for 357).
The hammer must not move rearward when the gun is lifted.
The hammer should lift 3 1/2 lbs without going into the cocked position.
So, it isn't an issue with the actual firing pin's dimensions, it is an energy transfer issue. A longer firing pin then might well address the symptom of the problem, but wouldn't actually fix the problem.
and I don't know how true this is a comment was made that the firing pins had a near minimal protrusion to allow passing the California Drop Test. If this be the case perhaps that is why the spring pressure is high on the gun. The firing pin is inertial so the harder the hammer hits it the further it will protrude unless it hits the end of its travel. Perhaps, somehow, the firing pin spring was damaged is another thought.
That didn't fix the gun though.
I fired around 350 - 400 rounds of .44 spl. rounds and 150 .44 magnum rounds with no light strikes. I changed the mainspring and started getting light strikes, changed back and the problem persisted.
I sent the gun (S&W model 69 2.75") back to S&W and it has not been returned as of today. 12-23-17
I had this exact issue with a performance center 686. It wouldn't reliably fire in double action. S&W put a longer firing pin in it as a fix. It works as it should now, but I have misgivings about the durability of that "repair".
Time will tell.
Do you have the opportunity to measure the new firing pin? I am really curious whether it is an extra long firing pin, or whether it is just at the maximum standard spec.
I believe that the nominal length for S&W frame mounted firing pins is .495. Most current firing pins are close to this length, but there have occasionally been some that are a bit short. My cut off is .492. If I find one shorter than that I replace it with a stock S&W pin that is up to correct spec. If I could not get a S&W pin that was within a couple thousands of .495, then I would use a standard length pin from another brand. Most extra length pins are around .510, and I personally would be cautious about using one in a duty gun. I have not heard of any extra length pins from S&W, though I could be wrong.
Some years ago, the standard pins from S&W were shorter, sometimes .485 or less. Most guns with strong factory springs worked OK with these pins, but they really are a bit short. If I see one, I will replace it.
This information about firing pins, as well as lots more info about trigger tuning and the causes of light strikes, can be found in my article which is referenced in post #5 of this thread.
S&W says the problem was a broken firing pin! I did not think to measure the pin before I sent it off. New pin measures .496 ,so I guess it is a standard pin.
Hammer.....stock, I never touched it.
Mainspring.....stock, ". "
Trigger return spring.....was a Wolff 13# spring.
Rebound slide......I had polished the contact surfaces.
Firing pin spring......stock.
No parts were returned, so I don't know the length of the broken pin. The only conclusion I can make is that the FP must have broken about the time of the spring swap, causing the light strikes that I blamed on the spring.
They DID NOT correct the 15# plus double action pull as I requested. No mention of it in the paperwork.
I will take it to the range this weekend to verify that the problem is corrected. Range report next week!
They usually won't touch it if it is within factory spec.
If you had requested that the action be tuned, that would have gone through the Performance Center...and required a completely different workorder to be completed
I fired 150 rounds total, 100 rounds of .44 special handloads and 50 rounds of factory .44 magnum with no misfires or light hammer strikes. All went "bang" as expected. Accuracy was good at 15 and 25 yards, and should improve as I get accustomed to the trigger, or have an action job done.
Don't know why they changed out the stock parts unless it was just caution on the part of the 'smith who worked on it, but it is working fine now.
I will not be using this gun for EDC until I have put more rounds through it and I feel comfortable that the problem is fixed. That will be about another 200 - 300 rounds without incident.
200-300 rounds of 44 is worth a lot of money. I would have just taken the shortcut directly to my gunsmith, if an action job was projected anyway.
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