Stupid Firing Pins!!

[BartCarter]

So, has anyone had premature breakage of a Colt firing pin in a Colt bolt?

Has anyone had a problem with a CMMG in a CMMG bolt?

Has anyone had a problem with a Wilson pin and what bolts take a Wilson pin?

 

I believe these pins and bolts are all comparable, but don't know for sure.

 

We should make a chart of pins and bolts.  Doesn't make sense to guess.  What do you think?

 

[v1911]

Are these firing pins MIM, cast or billet?

[longbeard]

Most seem to be made of tool steel.  The upscale ones are stainless steel.  How they are made I do not know.  The tool steel ones I had all broke in the middle.  The stainless one broke off at the head. Makes me think that they are being flexed by either being too long like when you bow a stick into the ground.  The harder steel broke at its weakest point (the joint at the top) while the softer steel just fractures in the middle.  

 

Thoughts?

 

 

 

 

[JAFO]

4 hours ago, longbeard said:

What exactly is causing the breakage?  I've seen speculation on this forum, but do we know for sure?

 

 

NFA seems to believe it's the strike angle of the hammer on the pin (from their website)...

 

"**NOTE:  Many Aftermarket drop in triggers use modified hammers which may not reset properly, or hit the firing pin square on the carrier which could cause firing pins to bind and snap.  We recommend using only MILSPEC hammers with any 9mm, .40, or .45 blow back bolt carrier groups."

[longbeard]

1 minute ago, JAFO said:

 

NFA seems to believe it's the strike angle of the hammer on the pin (from their website)...

 

"**NOTE:  Many Aftermarket drop in triggers use modified hammers which may not reset properly, or hit the firing pin square on the carrier which could cause firing pins to bind and snap.  We recommend using only MILSPEC hammers with any 9mm, .40, or .45 blow back bolt carrier groups."

That's gotta be what's going on. A sharpie and some dry fire should show this.  I may try later.  Curious....

 

[Tampa-XD45]

3 hours ago, BartCarter said:

So, has anyone had premature breakage of a Colt firing pin in a Colt bolt?

Has anyone had a problem with a CMMG in a CMMG bolt?

Has anyone had a problem with a Wilson pin and what bolts take a Wilson pin?

 

I believe these pins and bolts are all comparable, but don't know for sure.

 

We should make a chart of pins and bolts.  Doesn't make sense to guess.  What do you think?

 

Looks like we have multiple firing pin threads.  My CMMG pin broke after about 5,000 rounds in my CMMG bolt.

[JohnnyD]

My Taccom Firing pin that came with my ULW upper broke after only 600 or so rounds.  Taccom kindly sent a replacement out at no charge but I haven't tried it yet, just showed up yesterday.  Mine didn't break in half but the tip was broken off.

 

Running a Hyperfire 24 3G trigger and my own reloads using Winchester SPP.

 

Also ordered 2 CMMG firing pins to try out.

[MikieM]

My belief is that the hammer, for whatever reason, is striking the head of the pin off center causing it to flex along its axis. 

Over time the pin suffers enough fatigue to break.

Edited May 1, 2018 by MikieM

[kooyahdesigns]

Deng i should buy a few firing pins for myself. Nothing worst than equipment breaking in the middle of a match.

[Tan40]

I have also heard it the angel of strike for the hammer.  I wonder if a JP standard two piece trigger will fix this, vs the drop-in types??

[L9X25]

I have the "standard JP two piece trigger" with the reduced power (yellow) spring and broke a pin in less that 1,000 rds.

[Patrick Scott]

What do you guys think the cause is here?  Versus 5.56/.223 pins the 9mm pins are shorter, run a return spring and what else?  I wish someone would/could tell me that its the fact it runs a spring due to softer pistol primer cups. Id ditch the spring and run rifle primers, lol. 

Edited May 7, 2018 by Patrick Scott

[Patrick Scott]

On 5/1/2018 at 3:50 PM, MikieM said:

My belief is that the hammer, for whatever reason, is striking the head of the pin off center causing it to flex along its axis. 

Over time the pin suffers enough fatigue to break.

Im not picturing why this would not effect .223/5.56 guns as well. Help me out here.  Less protrusion from the rear?

 

Edited May 7, 2018 by Patrick Scott

[BartCarter]

25 minutes ago, Patrick Scott said:

What do you guys think the cause is here?  Versus 5.56/.223 pins the 9mm pins are shorter, run a return spring and what else?  I wish someone would/could tell me that its the fact it runs a spring due to softer pistol primer cups. Id ditch the spring and run rifle primers, lol. 

 

I would say the rounded head of the pin.  It has been suggested that rounding off the head of the 9mm firing pin would make the hammer strike more in the center of the pin, lessening the impact angularity.  I have notices that my 9mm pins seem to strike on the edge, not the center of the head.  Makes sense to me.

[MikieM]

I like the idea of rounding the head of the pin, myself. Making sure the pin doesn't shorten, of course.

[JAFO]

Has anyone examined at what angle their hammer would strike their pin in battery?  Without a cut-away upper/lower, I suppose the only way to do it would be to remove the upper and position the BCG where it would be relative to the lower, then see how the hammer face would impact it.

Edited May 8, 2018 by JAFO

[L9X25]

I can tell you that the hammer face is not perpendicular to the firing pin at the point of impact.  At rest against the bolt it may be perpendicular, or very close to it, but it is short of perpendicular at impact.  I installed a pin with a broad striking surface and the impact was exclusively at the bottom edge of the impact area and I suffered with a high percentage of light strikes. I also noticed that the firing pin was banging around inside of the tunnel, on it's way to the primer (from the torque induced from the off-center hit) and there were marks on the pin from the impacts.  I machined away the head impact area, forcing it to strike much closer to the center, and the light strike problem went away along with the marks along the top of the firing pin.    

[Patrick Scott]

I have been cruising some non competition places lately with this issue at mind. So far a former Colt employee and at least 2 Colt armorers have told me that with the Colt guns this was/is not an issue.  Here is an interesting snippet from one guy:


"Dude. I was maintaining a f*#king fleet of full auto Colt SMGs. We had more in service globally than anyone and they all circulated through my shop.
I can say with 100% certainty that I saw ZERO NADA NONE ZILCH broken firing pins. We saw dozens, if not hundreds of broken lower receivers. Hundreds of loose barrel nuts. Thousands of broken hammer trigger pins...
Not a single broken firing pin on a Colt SMG. I replaced a few that were lost in the cleaning area. Saw plenty of bad firing pin retaining pins too."

If this is the case and so far 3 out of 3 guys have told me it is, then what is Colt doing right? What are we doing wrong?   Maybe its our non-milspec triggers, maybe its the quality of parts? 

Edited May 9, 2018 by Patrick Scott

[BartCarter]

39 minutes ago, Patrick Scott said:

...What are we doing wrong?   Maybe its our non-milspec triggers...

OK, I'm voting for this.  Or is the Colt firing pin different?

[Patrick Scott]

1 minute ago, BartCarter said:

OK, I'm voting for this.  Or is the Colt firing pin different?

The Colt pin(from pictures I have seen) looks like all the "standard" pins out there. I don't know what material they are using or how they harden it. I also can't find a good enough picture to tell how much of a radius they are using at the "step down".  Having a hard time finding a legit Colt one in stock to buy. 

[MikeRush]

Just now, Patrick Scott said:

The Colt pin(from pictures I have seen) looks like all the "standard" pins out there. I don't know what material they are using or how they harden it. I also can't find a good enough picture to tell how much of a radius they are using at the "step down".  Having a hard time finding a legit Colt one in stock to buy. 

 

https://www.brownells.com/rifle-parts/bolt-parts/firing-pin-parts/firing-pins/ar6951-9mm-firing-pin-prod4829.aspx

 

The transitions appears in the first picture, to my eyes, different than the picture you posted a couple of days ago. In the other photo angles it look comparable, so I think comparison would be difficult without having the two side by side.

 

The QC10 pin has a nice radius there. I haven't broken a pin yet and have done quite a bit of shooting.

 

I think extremely high hammer impact velocities don't help. I also think it might be at least in part a bolt problem. I have said this before, but some bolts seem to eat firing pins while others never have a problem. I guess if someone had a borescope they could look at the firing pin channel.

 

 

[sandrooney]

I just replaced a broken FP in my GMR 15 and noticed the new firing pin was rounded off where the hammer strikes it. I noticed this while cleaning the gun and unfortunately I had already thrown out the broken pin so I could not compare the two. I bought the gun last year and the spare firing pins a couple months ago. Maybe this is JPs attempt at a fix.

[Patrick Scott]

2 minutes ago, sandrooney said:

I just replaced a broken FP in my GMR 15 and noticed the new firing pin was rounded off where the hammer strikes it. I noticed this while cleaning the gun and unfortunately I had already thrown out the broken pin so I could not compare the two. I bought the gun last year and the spare firing pins a couple months ago. Maybe this is JPs attempt at a fix.

Got any pictures of the new one?

[MikieM]

On 5/7/2018 at 11:21 AM, Patrick Scott said:

Im not picturing why this would not effect .223/5.56 guns as well. Help me out here.  Less protrusion from the rear?

 

 

Other than the length of the pin I have no idea.

One of our local gun builders thought it was simply the nature of the beast, and by that I assumed he meant the violent action of the bolt in the blow back system wreaking havoc on the firing pin. 

[Patrick Scott]

3 minutes ago, MikieM said:

 

Other than the length of the pin I have no idea.

One of our local gun builders thought it was simply the nature of the beast, and by that I assumed he meant the violent action of the bolt in the blow back system wreaking havoc on the firing pin. 

That makes some sense to me, but what the Colt mil/leo guys are telling me kind of makes me thing that's not the case.