Changing the firing pin on STI

[zero_down]

I have an open STI that works great 98% of the time. There are times (and only during rapid fire) that the hammer goes down and there's no bang. At first I thought that the hammer wasn't staying back when the slide cycled cuz I would push the trigger and nothing. But then I would cylce the slide, fresh round would get ejected, and then I could move on. Upon examining the round that was ejected, I would see a small impression on the primer which leads me to believe that the firing pin is hitting it just not enough to set it off. I've had people tell me that I need a longer firing pin and I did get one, but now the package says that I should have a gunsmith install it. I realize that everyone needs to say that for legal reasons, I've even seen grips that say "should be installed be a gunsmith". Do I really need to send it off or can I do this on my own? Any ideas or opinions.

[G-ManBart]

Yeah, you should be able to put it in yourself. Make sure it doesn't protrude from the breachface when back of the firing pin is pushed flush with the firing pin stop....otherwise you could get a slam flire (not very likely with a modern slide and name-brand firing pin.

Now, the reality is that in almost every case, when you get those very slight dents in your primers and they don't go off, it's not the firing pin, it was a high primer. If the gun is normally hitting the primers solidly a light hit isn't going to happen unless you magically got a lighter push from the mainspring....not gonna happen. A extended firing pin is more likely to set off a slightly high primer, but that's not why we use them. We use them to prevent primer flow back into the firing pin hole.

Short version, check the primers on your loaded rounds. I like to put them in the 100ct Dillon ammo boxes so I can see and feel every primer quickly. If one is even a tiny bit high it will be very noticable. R,

[Pat Miles]

Are you familiar enough with the gun to replace the firing pin? Not trying to talk down to you, just don't know your knowledge of the gun. If you need help, PM me and I'll help you through it.

Pay attention to the info Bart posted above regarding high primers.

CYa,

Pat

[GrumpyOne]

It should be the same as replacing the firing pin in a 1911. Just make sure you change it under non protected flourescent lights!

[BMartens]

G-man is right, check your primer seating and that should solve the problem.

If you can get the old firing pin out you should be able to install the new one.

[magicald_223]

I have used Dawson's extended firing pin and Matt McLearn's M2i firing pin and both work great! Both changed out seamlessly from my stock SV.

[Jasonub]

ill go for the limcat.

[magicald_223]

I haven't used the limcat, but I've heard good things about them.

[zero_down]

All i'm using if factory ammo so I'm not worried about high primers unless factory ammo has many variables which is usually doesn't. I know I can change out the pin cuz someone asked me to check if my firing pin was broken so I did take it out to check. But from what I hear from you guys, the length of the firing pin is not the problem. Perhaps it is the hammer not staying back with the cycle of the slide. BTW I tried using Atlanta Arms Ammo and my pistol doesn't like it at all. It'll shoot 2 or 3 then click but all I have to do is bring the hammer back again and pull the trigger again to make it go bang. That's why I thought it was the length of the firing pin.

[boz1911]

I assume the hammer is not following?? If so you need to try a leaf spring adjustment, more tension on the left finger. If the hammer is not following then I would try a new mainspring. Most people are running a 17-19 lb spring.

[zero_down]

thanks guys for all your help

[CocoBolo]

Intermittant problems in gun, cars, and computers, become a TE process. Before I ran out a bought a firing pin I think that I would pull the current pin and examine it for defects and clean the firing pin tube out with some CLP or CRC brake fluid and a Q-Tip. Since you asked about changing it you probably have not cleaned it. I clean my firing pin tube and extractor tubes out about every 5000 rounds to keep it running like a top. There could be enough crud in there to make it malfunction intermtttantly.

I think the jury is still out on Wolf Primers and they probably don't use Federal primers in Wolf ammo. None the less I recall the days of shooting factory ammo and I remember it was some nasty dirty caca the required frequent cleaning of the internals of the gun. I been at matches where shooters had trouble with factory ammo so its still within the real of possibility.

Just be careful to disassemble it and reassemble it in a place where you can find the firing pin if it escapes. I have one in my welding shop somewhere, it shot out about 2 years ago and still have not found it. It was a Tanfo with a firing pin block I know where the block is the land fill. An my wife won't let me clean guns at the kitchen table as I lost a firing pin in the kitchen for a while, it was stuck in the cieling.

[Duane Thomas]

What sort of ammo is giving you the problems? What is your mainspring weight?

Years ago a good pistolsmith told me something I have never forgotten: "Whenever a gun malfs, people never blame the ammo, they always blame the gun. But the fact is that most malfunctions are caused by the ammo." I'd look at your ammo before I started changing the gun. The fact that it's "factory" ammo does not automatically translate into it being good stuff to fire through a gun that has anything that could be described as a tuned action. For instance Wolf and S&B both feature notoriously hard primers.

[G-ManBart]

All i'm using if factory ammo so I'm not worried about high primers unless factory ammo has many variables which is usually doesn't. I know I can change out the pin cuz someone asked me to check if my firing pin was broken so I did take it out to check. But from what I hear from you guys, the length of the firing pin is not the problem. Perhaps it is the hammer not staying back with the cycle of the slide. BTW I tried using Atlanta Arms Ammo and my pistol doesn't like it at all. It'll shoot 2 or 3 then click but all I have to do is bring the hammer back again and pull the trigger again to make it go bang. That's why I thought it was the length of the firing pin.

Sounds like the hammer could be following to half-cock and when you press the trigger it drops a tiny amount and puts just a little mark on the primer. Have you gone through the gun from top to bottom....checked that the grip screws are tight etc? The fact that it happens with factory ammo, only shooting fast splits is a bit odd and loose grips can make guns do weird stuff. It could just be following from wear or because it needs some work on the sear spring....hard to say really. R,