Broken firing pins: Possible causes. Also... detail strip your guns!

This is a sequel thread that was spawned by these threads:
Lessons learned at the range about my EDC and mechanical parts failure.
Another broken firing pin!

Based on those discussions, what might cause firing pins to break?

1. Age / mechanical cycling / rounds fired / wear & tear.
2. Substandard aftermarket firing pins.
3. Flawed OEM firing pins (MIM?).
4. Out of spec firing pin channel or poor machining of aftermarket slides.
5. Sometimes shit just breaks.

Someone (@Bongo Lewi ?) suggested borescoping a high round rate factory Glock slide firing pin channel and comparing it to one of the aftermarket slides / builds with a history of a broken firing pin. Challenge accepted! Keep reading!

Several months ago, I had an OEM factory Glock firing pin break in my P80 PFC9 "EDC" at about 7,400 rounds.

More recently I had a firing pin break in a build with only 800 rounds through it. The pin was an aftermarket pin from an unknown source. The slide is from Heavy Armor Division (HAD), which has very a good reputation in this realm.

Looking through the breech, you can see the broken firing pin tip lodged in there sideways.

When I disassembled the slide, the broken tip fell out.

Could it be something in the way the firing pin channel was machined that is causing some stress on the firing pin? A plausible theory. Someone said, "Go look inside the channel! And compare it to a factory Glock!" OK! Here we go!

First up is a look inside the HAD slide on my P80 "Cobalt Celtic" build:

A little schmutz (brass flakes). I don't see any peening of the edges of the firing pin hole. Pretty unremarkable, IMO. Maybe some expert here will see something else?

There was also some discussion in the other thread about some peening on aftermarket firing pins vs OEM. So, I created a comparison composite. While the Shadow Systems (SS) example, on right, taken from a reddit post looks dramatic (especially after just 400 rounds), my SS firing pin with 1400 rounds (middle) shows a rather mild mark. Interestingly, the Glock firing pin (on left) shows a similar mark, with 10k+ rounds through it.

OK... Back to our regular programming... Let's take a look inside the firing pin channel in my Gen 2 Glock 19. I estimate at least 10,000 rounds through it since I bought it in 1996. Bear in mind that this is the FIRST time I've ever detail stripped the slide!

Whoa! There's gold in them thar channels, @Michele!

Halfway down the channel, there is what can only be described as a "sludge blob" (on right)!

I don't know if I should be embarrassed.... or impressed that the G19 has never had a malfunction. The only thing I've done to that pistol is field strip / clean and replaced a broken trigger spring and put in a new recoil spring.

Well... since I had it apart, I might as well clean'er up, eh? First thing I did was run some q-tips down the firing pin channel.

Then I "hosed it out" with some "Gunk Blaster" over some scrap paper. That would be a "good gold pan," eh @Michele??? LOL!

Wait! I didn't remove the extractor and firing pin safety plunger! Let's do that so I can flush this slide out from all angles.

Good golly, that's nasty! And this gun was running like the proverbial sewing machine!

After removing the extractor, I had to PRY out the firing pin safety plunger!

Let's spray down the firing pin assembly with some Gunk Blaster, too. Look at all the brass flakes!

I had to go several rounds with Gunk Blaster and q-tips and compressed air to get the firing pin channel cleaned out. After I THOUGHT I was done, I scoped the channel again. Nope! Not done! Still some brass down there!

So I went at it some more. And settled on this as "good enough!"

I cleaned the barrel, detail-stripped the frame, and cleaned it all. I put it all back together, and she feels smooth as silk!

So it seems the real "take home message" of this post is.... Detail strip-clean your freakin' guns once in a while!

So then... what is the story with the broken firing pins? My first thought always goes back to, "stick with OEM parts." HOWEVER, they can break, too! I have installed a machined billet aftermarket firing pin (Shadow Systems) in my PFC9 "EDC" gun, thinking that it may be better than the MIM factory firing pin. Or maybe sometimes shit just breaks?

In any case, I think it's prudent to stay on top of the maintenance of any firearm upon which you depend for self-defense or "SHTF." If it's a range gun, it's obviously less "critical." But even a well-maintained factory gun can fail. The trigger spring failed on my Glock 19 at about 7k - 8k estimated rounds. The spring was literally a couple of bucks. But a $2 spring can get you killed... unless... you have a BACK-UP. It's easy to have a back-up Home Defense gun... or two... or twenty. Carrying a back-up is a bit more tedious logistically. But it can be done. Do you? That could be another topic for another thread. I'll leave that to one of you to start!

What would be nice is if there was a reference that listed each internal Glock part and the recommended interval for replacement as a PREVENTIVE maintenance, so we can mitigate the chances of failure at the worst possible time.

 

[Bongo Lewi]

Excellent !

Diese Waffe ist sehr schmutzig!

The drek in the firing pin channel is why I ultrasound clean my guns. You still have to take them down all the way but the parts come out as clean as can be.

One note on your saga: I'd avoid using Qtips. They shred and can leave threads/fuzz behind. I started using Buy Swab-its® Swabs - Foam Cleaning Swabs - Gun Cleaning Products

 

[Racer88]

The drek in the firing pin channel is why I ultrasound clean my guns. You still have to take them down all the way but the parts come out as clean as can be.

Yeah... I need to get one of those! Recommendations?

The amount of junk that came out of just the firing pin channel was amazing. I think there was enough brass filings and chunks to cast a whole case! LOL! Also amazing is that the gun functioned perfectly with all that shit in there. Glock "perfection!"

One note on your saga: I'd avoid using Qtips. They shred and can leave threads/fuzz behind. I started using Buy Swab-its® Swabs - Foam Cleaning Swabs - Gun Cleaning Products

I actually have those! LOL! But, I have the rectangular ones like these, and I don't know if they'll fit in there... probably not.

I see they make some smaller ones, though.

 

[Bongo Lewi]

For just now and then, one gun at a time.. You can also clean your wife's jewelry. Metal watch bands... etc.

For a little more... something more heavy duty/commercial

There are literally dozens of models and sizes to choose from. They all work. The ultrasound transducers do wear out eventually but I would not worry about that unless you are using it every day.

These things work miracles on small carburetors that are clogged up. When I was restoring old motorcycles and scooters I discovered how effective ultrasonics are at cleaning parts that have a lot of internal nooks and crannies.

 

[Bongo Lewi]

The amount of junk that came out of just the firing pin channel was amazing. I think there was enough brass filings and chunks to cast a whole case! LOL! Also amazing is that the gun functioned perfectly with all that shit in there. Glock "perfection!"

I read an article in a Glock magazine they send to dealers. Maybe 6-7 years ago. It was about a guy who has a port-a-pot business that found a G17 while draining one of his plastic crappers. The gun was swimming in the most vile sludge for quite some time. He plucked it out, rinsed it off , reinserted the mag and popped off a few rounds. It was loaded. He did not tear it down and do a proper cleaning. Just a rinse.

Me? I would have donned a biohazard suit and run it thru a formal decontamination process. I guess that's why I'm not in the plastic shithouse business. A couple of times in my engineering days I had to visit a rendering plant and once a sewage treatment plant. I have never smelled anything so disgusting in my life. I have witnessed and can handle horrific gore, blood, guts.... but the smell of rotting meat or shit makes me hurl.

 

[bkbrno]

The HAD slide has a sharp shoulder where the tip protrudes. The Glock slide looks like this area has a rounded edge. Was it out there or did it get there from wear? That is the question.

 

[Racer88]

The HAD slide has a sharp shoulder where the tip protrudes. The Glock slide looks like this area has a rounded edge. Was it out there or did it get there from wear? That is the question.

It would only matter if the firing pin was rubbing on it. And if it was rubbing there, we'd see wear patterns or peening in those places. I don't see any evidence of contact on those shoulders.

The only way the shoulders of the firing pin hole in the breech would cause the breakage of the firing pin tip (IMO) is by deflective contacts / strikes. I don't see evidence of that. We'd also see corresponding wear marks on the sides of the firing pin tip. Not seeing that, either.

I don't think (at least in these cases) that the firing pin hole or slide machining is involved at all with the breakage of the firing pin tips. I submit that it's flaws (inclusions, voids, crystallization) in the MIM causing metallurgical failures after repeated impacts with primers. The tip of the firing pin isn't touching the breech, IMO.

In other words... Sometimes shit breaks.

 

[Bongo Lewi]

A pin that's free of defects is going to be most durable if it hits the primer 'square'. Meaning... the applied force or moment is applied equally to the entire pin. A shearing force - in simple terms the pin is not hitting the primer square - would cause stress to the part and ultimately it would fail.

 

[Racer88]

A pin that's free of defects is going to be most durable if it hits the primer 'square'. Meaning... the applied force or moment is applied equally to the entire pin. A shearing force - in simple terms the pin is not hitting the primer square - would cause stress to the part and ultimately it would fail.

That would assume a perfectly symmetrical deformation of the primer (to eliminate any shear / lateral forces). Right?

In any case, thousands of impacts, even if theoretically in purely compressive vector, on a relatively thin piece of metal... any variances in the casting... it's going to fail eventually. The question is HOW "eventually?" And the 90-degree angle of the thin tip where it joins the main body of the firing pin might be a stress riser (even with thousands of compressive impact shocks)... which is exactly where it broke.

I'm still going to stand by my position that it's not the slide here causing the failure of the firing pin tip. Of course, I'm speculating and could be wrong.

In the case of the most recent failure (at 800 rds), the firing pin was aftermarket. So we might safely assume it was of inferior quality. So, I've installed a factory pin in it. If it breaks again in a similarly short time, then we might be reasonably doubtful of my current theory.

In the previous incident, the firing pin was OEM, but it had 7,400 rounds on it. So, while that's not a LOT of rounds, it's also not just a few. The hardness of the primers could also be a factor. The vast majority of the ammo fired was CCI, and I read somewhere that CCI primers are considered "hard."

 

[Alex]

I had an aftermarket billet firing pin break in one of my S&W revolvers. I dry fired it quite a bit and it did break during dry fire. Maybe it was designed for compressive force, not the unsupported tensile force of dry fire?

Not that I have many optics on pistols but would one of those survive a bath in an ultrasonic parts washer? I usually clean my guns in the Safety Kleen parts washer at work but my boss walked up to talk to me while in the process this weekend. It would probably be wise to get a home gun cleaning setup...

 

[Racer88]

I had an aftermarket billet firing pin break in one of my S&W revolvers. I dry fired it quite a bit and it did break during dry fire. Maybe it was designed for compressive force, not the unsupported tensile force of dry fire?
View attachment 24145

Not that I have many optics on pistols but would one of those survive a bath in an ultrasonic parts washer? I usually clean my guns in the Safety Kleen parts washer at work but my boss walked up to talk to me while in the process this weekend. It would probably be wise to get a home gun cleaning setup...

Good point about dry fire. I know there is some controversy about it, even in guns that are supposedly "safe" to dry fire. Now that I think about it, the PFC9 with 7400 rounds on it was also dry fired probably hundreds of times. Hmmmmm....

But the "Cobalt Celtic" with the aftermarket firing pin was not dry fired much at all.

 

[Racer88]

Not that I have many optics on pistols but would one of those survive a bath in an ultrasonic parts washer?

I would not submerge an optic in an ultrasonic. Definitely remove it first.

 

[bkbrno]

I would NOT but an optic in an ultrasonic. Water will get into the electronics. Sights are only rated for 1 or 2 meters of water depth if at all. The lens coatings will probably erode away. I suppose you could suspend the slide with the optic out of the water but my experience that stuff moves around a lot in the bath. Good luck keeping it in one spot.

A test to see if your ultrasonic is working is to put a single strip of aluminum foil vertically in the bath. It will eat holes in it very quickly. That is not what it does to solid metal but it isn't too far off. Don't hold on to parts or put your hands in the bath when the ultrasonic is on. I tested it for you. It doesn't cause pain but it feels like you are doing something bad to your body. More than a tingle, not quite stinging. Experts say bad thing happen to the muscle and skin. I'll take their word for it and I keep my mitts away when it's on now.

 

[Michele]

Ok, @Racer88 - 2nd time I’ve remarked on the upper parts- those are NOT HAD.
The upper parts could be from any number of venders on our vender list. I buy upk from any/all of our great parts providers. I can tell you they are not LWD, HAD or OEM.

That shiny stuff is obviously brass

 

[Racer88]

Ok, @Racer88 - 2nd time I’ve remarked on the upper parts- those are NOT HAD.
The upper parts could be from any number of venders on our vender list. I buy upk from any/all of our great parts providers. I can tell you they are not LWD, HAD or OEM.

That shiny stuff is obviously brass

Ah, OK! Assumption on my part since they arrived together.

I'll edit that to "unknown."

Wait... was it possibly Rocky Brass for the parts?

I wish that my guns turned spent ammo into gold, eh??? LOL!

ETA: According to my build diary thread, the LPK was Rocky Brass and UPK was HAD. That doesn't mean it was accurate, but I recorded it that way for some reason. Not that it really matters.

PGB Award PF940C "Cobalt Celtic" Build Diary

Looks amazing Racer. The accessories match the etch , didn’t know y had that cool release.where’d ya get that Thanks! I got the mag release from NDZ. They offer free laser etching from a huge library of icons, logos, patterns: https://ndzperformance.com/ndz-custom-stock-image-library-18571/...

www.patriotgunbuilders.com

 

[bkbrno]

Pictures can be deceiving and may show things that aren't actually there. Sorry to beat this dead horse but the OEM slide has machining cuts that the HAD slide does not. The top and bottom of the slot are rounded. The center of the slot had a rounded divot machined in. I don't think Glock would put them there because they look pretty.

The firing pin would have to be forensically examined to determine how it failed. I am no expert in this but I studied enough aircraft failures to know that there are several failure modes and it takes special tools to determine how it failed. Tools like an electron scanning microscope. Anyone have one sitting around? A jeweler's loupe and a hunch won't cut it here.

Side to side movement seems like an obvious failure mode but what if Glock"s testing revealed top to bottom stress caused failure? That would explain the rounded edges on the top and bottom. In my mind, that is were the most stress happens when a round is cycled. It would also explain why the tip is so tall compared to convention of a round firing pin at the time the Glock was designed.

 

[Racer88]

I am no expert in this but I studied enough aircraft failures to know that there are several failure modes and it takes special tools to determine how it failed. Tools like an electron scanning microscope. Anyone have one sitting around? A jeweler's loupe and a hunch won't cut it here.

Exactly. We're all just guessing. I was looking into buying a scanning electron microscope, but we just don't have room for it in the house.

As I said earlier, If it happens AGAIN (with an OEM pin) in a relatively short time / rounds fired... We might more reasonably chalk it up to something with the slide (or something else).

But for now, I'm going to assume it was the aftermarket pin having a flaw of some kind. So, the reasonable thing to do is just replace the pin with OEM factory and see what happens. I don't shoot this gun as much as my EDC. It's pretty much a range toy. So, it could be a while for a problem (if there is one) to show up.

 

[Bongo Lewi]

Tritium night sights are safe in an ultrasonic. Red dots... anything active with electronics? No bueno.

This (below) is what I am referring to in my previous post. Intentionally exaggerated to make it more clear what I mean by shear having an effect on the usable life of the striker. Striker guns are really not precision devices. Still, I think if you look at your spent cases, and the primer is not dented close to the center, what you see on the right of the simple diagram below may be what's happening. Left good, right bad. Crud in the channel is one possible cause. Another possibility is a third party slide striker channel may not be the same diameter as a Glock OEM. Off by a hair, perhaps. More slop, more of a chance of the striker not always being 'plumb'.

 

[Racer88]

What's our vector, Victor?

View: https://www.youtube.com/watch?v=fVq4_HhBK8Y

 

[Bongo Lewi]

Have you ever seen a grown man naked?

And don't call me Shirley.