[Sammy Fan]

Just experienced a few "failure to fire" at the range. The firing pin would dent the primer but it would not go off. Put the rounds in another gun, they fired OK. This started to happen a few months ago, but it is now happening more regularly.
Read somewhere that the pin should protrude .030 in out of the breech face with the hammer against the head of the pin. Is this the norm? This certainly is not the case here, I can see that the pin is just flush with the breech face when the head of the pin is pushed flat with the firing pin stop. What is the normal length for the firing pin? Can this pin be worn too short? Are there extra length pins available?

 

[10mmfan]

The firing pin should not protude from hole when pushing hammer forward. Your problem is probably too weak mainspring which should be replaced with stock (23 lb), or could be a bent firing pin.

 

[lesthemess]

Make sure your firing pin spring is installed correctly. That is tight end to rear of slide.


lesthemess

 

[feedramp]

10mmfan is correct. The end of the FP should not extend beyond the breechface when the hammer is all the way down, and pressing against the FP. From your description, it sounds like your FP is the correct length. The weak strike could be due to:

weak mainspring,

hammer binding as it moves toward the FP,

bent or broken FP,

distorted, binding, or broken FP spring,

obsruction/debris in the FP channel in the slide.

Another possibility is that the slide could be out of battery by a mm or two. The hammer could still fall from a trigger pull, but the force of the strike on the FP would be lessened. You might want to check to see if the slide is in full battery when this happens.

One way to check the free movement of the FP in its channel is to use a toothpick or something similar to push the FP forward with the hammer at full cock, as if you were going to remove the FP stop. Move it back and forth to check for free movement, grinding, etc.

That's all I can come up with for now.

Good Luck.

 

[WalterMitty]

As was already said, the firing pin should not protrude through the hole with the hammer resting on it. The system works through inertia. The hammer whacks the firing pin hard enough that it travels forward through the hole and hits the primer.

A generic layman's test for the firing pin system is to cock the empty pistol and put a pencil with an eraser on it down the barrel, eraser first. Pull the trigger with the muzzle pointing up and the pencil should go a good 3 - 4 into the air. If the pencil doesn't fly out, or just dribbles out of the muzzle, you have a firing pin system problem to troubleshoot.

On the other hand, if you reload (didn't you say you were reloading somewhere else?) your problem could be "high" primers. If your primers aren't fully seated for some reason, sometimes the firing pin will seat them for you without lighting them off. Most times, if you try to fire them again they will fire.

High primers is a common reloading problem most reloaders have experienced. Check your brass that did fire. If you've got a nice dent in those primers, chances are it isn't the gun. If you can poink the ceiling with a pencil it almost certainly isn't the gun.

To check your ammo rub your fingertip over the primer. They should all be slightly below the face of the case head. Any that are higher, even a little bit, are probably not fully seated and may not fire the first time.

 

[M-614]

If the pistol in question is a Series 80 Colt, could the problem be that the trigger linkage is not lifting the firing pin block in the slide enough for unobstructed firing pin travel? If this is not the case I would also guess weak mainspring.

Larry

 

[George Smith]

Stock firing pin is 1.280 ish.
all good points above.
Check the series 80 by holding the hammer back and pull the trigger. use something to push the firing pin Like above and make sure it is not binding. One of the most common is the over travel screw is toooo tight and not allowing the lever to push the plunger up all the way.

On the high primers, as the firing pin hits them it also seats the primer and takes away the force. The anvil has to be against the brass to fire.

Usually 1911 will fire reliably with down to an 18# main spring.

also check for the hammer strut rubbing the inside of the grip safety, side of the ejector slowing the hammer fall and all the very good suggestions above.

On the pencil test, we use a widgit and are looking for 3 feet or more. the widgit (packmayer) is always the same.

good luck
geo ><>

ps
the XL firing pin was for super 40 and 9x23
used in competition guns. it prevented primer flow back with the hotter loads. with the hammer down it protruded .030 (probably what you read) and prevented primer flow back.
(a primer flowing into the firing pin hole, getting sheared off when the barrel drops down out of battery and the remaining part of the primer giving you a light hit on the next round. easiest way to see it is look at the hit on the primer, if it is really weird you know where to look)

also check for bent firing pins

 

[Sammy Fan]

Checked the FP length: 1.290 in and it is straight. Also did the "Pencil Test". It took off vertically to just a little over 2 ft. Measured the indentation on the primers of the unfired rounds, they measure approx. 0.050 in across while the indents on the spent casings were almost 0.080 in.
Cleaned the FP channel as well, not extremely dirty but a fair amount of dirt or grime on the Q Tips.
I suspect it may have been a weak main spring and dirty FP channel that caused the misfires.
Thank you all for the info.