Minor malfunction / need advice

[Ner]

So

 

I was testing some stuff when the occasional uncontrollable bumpfiring happened. After that i have found that the firing pin is done.

 

It's barely noticable so i put some slowmo to you guys.. hehehe :]

https://www.youtube.com/watch?v=wiVYwbnERwM&ab_channel=FxPew

 

So 

What do you think

 

A: Broken Pin caused these extra shots

or

B: s#!t occurred and broke my Pin at the end

 

*sound from Who Wants To Be A Millionaire  tv show*

 

 

 

[copterdrvr]

Bet they were pi$$ed at the range when they heard THAT go off!!!

 

Just curious-is it a new build and whose trigger is installed?

 

When my firing pin broke in the same location, the gun quit shooting.....

 

During my initial build I had a trigger with too light a trigger pull and it would occasionally double-didn't go fully monty though......

[BillChunn]

Need more information.  

 

Did you continue to hold the trigger rearward when the full-auto firing started?  

If not, was the broken firing pin protruding from the bolt's breachface and really, really stuck there?

 

BC

Edited December 31, 2020 by BillChunn

[Ner]

Facts:

• ECL trigger with lightest springs for a year or so

• For this test the build was shortstroked balls deep. I don't think it's related coz it's only 1 coin more than my usual build

• I released the trigger right after 2nd shot. / total of 30 rounds 

• After "the thing goes Traaa" maneuver i loaded some more rounds and only then i realised it's not working any more and the pin is done. 

• Pin is broken in two places. Tip and the middle

• Later evening i found that (see image) Dunno how and dunno how will it affect my shooting from now on. Any ideas? could it be a tip of the pin damaging and making this hole?

 

 

[BillChunn]

Ok, this is just a guess.... If that small piece of broken breechface was sticking out (see picture below) it acted like the firing pin.  It would have hit the primer and set off the round.  The carbine would have cycled and put another round into the chamber and the bolt came forward, setting off that round.  Repeated until magazine was emptied.

 

Bottom line, in my opinion that bolt has to be replaced.

 

BC

[Ner]

47 minutes ago, BillChunn said:

Ok, this is just a guess.... If that small piece of broken breechface was sticking out (see picture below) it acted like the firing pin.  It would have hit the primer and set off the round.  The carbine would have cycled and put another round into the chamber and the bolt came forward, setting off that round.  Repeated until magazine was emptied.

 

Bottom line, in my opinion that bolt has to be replaced.

 

BC

hmmm

[robertg5322]

3 hours ago, BillChunn said:

Ok, this is just a guess.... If that small piece of broken breechface was sticking out (see picture below) it acted like the firing pin.  It would have hit the primer and set off the round.  The carbine would have cycled and put another round into the chamber and the bolt came forward, setting off that round.  Repeated until magazine was emptied.

 

Bottom line, in my opinion that bolt has to be replaced.

 

BC

Or file off the burr.

[copterdrvr]

looks more like an indentation rather than a protuberance to me......

[Ner]

15 minutes ago, robertg5322 said:

Or file off the burr.

What burr? it's not a burr it's more of a notch

gonna stick it with a booger

 

 

Edited January 7, 2021 by Ner

[robertg5322]

14 minutes ago, Ner said:

What burr? it's not a burr it's more of a notch

gonna stick it with a booger

 

 

Once the protruding piece is removed, and and firing pin replaced, wouldn't function be returned to normal? Not optimal to have a small divot in the breechface, but probably not a problem either.

 

Bigger question is what caused the damage? The nose of the firing pin breaking off and getting jammed between the next round and the breechface?

 

In any event, JB Well will fix it right up... 

[Ner]

21 minutes ago, robertg5322 said:

Once the protruding piece is removed, and and firing pin replaced, wouldn't function be returned to normal? Not optimal to have a small divot in the breechface, but probably not a problem either.

 

Bigger question is what caused the damage? The nose of the firing pin breaking off and getting jammed between the next round and the breechface?

 

In any event, JB Well will fix it right up... 

I was about to test it out but Corona hit the fan and i'm lockdowned now

 

I realy hope that the problem was in a Firing pin spring *see image* Left combo is a failured one. Right one - new. See how spring being much shorter. Fired only 2-3k rounds with this spring+pin..So it could be the cause. Traaa started ..broke the tip of the pin..Tip made a hole.. Or a piece of breechface made a Traaa as a Comrade 5322 said

 

Btw thanks for the idea with JB Well ! Gonna try it

[jerseyglock]

2 minutes ago, Ner said:

 

Btw thanks for the idea with JB Well ! Gonna try it

 

Don't waste your time with JB weld. Just go buy a new firing pin.

[Ner]

2 minutes ago, jerseyglock said:

 

Don't waste your time with JB weld. Just go buy a new firing pin.

omg it's not for fixing a pin! :DDDD 

it's for fixing a hole in the bolt 

[Ner]

cold welding cured my Pin ! wamen!

[robertg5322]

1 hour ago, Ner said:

I was about to test it out but Corona hit the fan and i'm lockdowned now

 

I realy hope that the problem was in a Firing pin spring *see image* Left combo is a failured one. Right one - new. See how spring being much shorter. Fired only 2-3k rounds with this spring+pin..So it could be the cause. Traaa started ..broke the tip of the pin..Tip made a hole.. Or a piece of breechface made a Traaa as a Comrade 5322 said

 

Btw thanks for the idea with JB Well ! Gonna try it

Comrade 5322, I chuckled.

 

I was half-joking about the JB Weld in the divot, probably not necessary, but probably won't hurt either.

 

The firing pin springs in these guns almost seem like an afterthought. Most of the ones I've handled seem pretty flimsy for what they're doing.

[robertg5322]

1 hour ago, Ner said:

cold welding cured my Pin ! wamen!

Now take it to the buffer, and voila!! Good as new.

[BillChunn]

This is getting down right funny.....

 

But back to the original question.  New theory: 

 

Something that was made out of a harder metal than the bolt made that indentation.  When the firing pin tip broke off (firing pins are usually pretty hard) it came through the breechface hole, and got trapped near the primer and then was lodged there when the round off.  This caused it to stick into the breechface, making the indentation.  Notice it's inside the primer circle on the breechface which would cause the round to go off.  If it wasn't really stuck there, then it "walked" a bit when the next round came up out of the magazine causing the semi-circle indentation.  If it was still in that area, it would have set off the next round, etc. etc. etc. hammering it into the breechface.

 

Is the width across the indentation about the same size as the firing pin tip?

 

JB-Weld that puppy up and load up 30 more rounds and see if it does it again.... with the cold welded firing pin of course..... 

 

BC

 

 

Edited January 7, 2021 by BillChunn

[Ner]

10 hours ago, BillChunn said:

Is the width across the indentation about the same size as the firing pin tip?

No, the missing tip is much-much bigger, like 10 times..Other thing to consider is..If a broken tip was sticked there i think it would not let the ammo to being chambered and would cause an out_of_battery explosion..or could..dunno..m.b. someone wants to test it? Stick something there and load 30 rounds..anybody ...? guys...?

Edited January 8, 2021 by Ner