Author Topic: Dry firing and the firing pin block  (Read 769 times)

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Offline NMShooter

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Dry firing and the firing pin block
« on: January 13, 2020, 05:00:47 PM »
I've read that dry firing the CZ75 will damage the firing pin block. Explain to me how the damage occurs. When the trigger is pulled, the trigger bar moves the firing pin block lifter which lifts the firing pin block out of the way of the firing pin, so after the shot breaks does the block drop and come in contact with the firing pin on its return to the rear? It seems as long as there is rearward pressure on the trigger the firing pin block will remain out of the way.

Offline rckendall

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Re: Dry firing and the firing pin block
« Reply #1 on: January 13, 2020, 05:59:21 PM »
I think the pin that gets damaged from dry firing is the firing pin retaining pin. It gets the full force of the firing pin when dry firing, not damped by it hitting the primer.

Richard

Offline Tok36

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Re: Dry firing and the firing pin block
« Reply #2 on: January 13, 2020, 06:09:36 PM »
^^ This, it is the Firing Pin Retaining Pin in the slide that can take damage.
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Offline M1A4ME

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Re: Dry firing and the firing pin block
« Reply #3 on: January 13, 2020, 06:37:39 PM »
The firing pin shaft has a notch, or two, cut into it inside the slide where you can't see it.  Pull one out some time to replace the firing pin retaining pin and you'll see them.

The notch in question is cut long enough to allow the firing pin to move forward enough to strike the primer and rearward enough to protrude slightly through the back of the slide so that hammer can hit it.

The firing pin retaining pin sits in the slide so that it contacts the front and rear of the notch in both directions of travel.

When moving rearward the firing pin is only moved by the firing pin return spring.  A small relatively weak spring that doesn't move the firing pin fast enough to cause damage/wear on the front of the notch or the front of the firing pin retaining pin.

When the hammer strikers the firing pin it is moving forward much faster as it has to set off the primer.  If the firing pin hits the primer first it is slowed down by contact with the primer and the firing pin (back end of the notch) may not contact the firing pin retaining pin at all.

Without a primer, or snap cap, or o-ring placed in the notch in the rear of the slide the firing pin will slam forward and slam the back of the notch in the firing pin into the rear of the firing pin retaining pin. 

Look around in the forum you'll see pictures of damaged firing pin retaining pins.

Why does the firing pin damage the firing pin retaining pin instead of the other way around?  A firing pin cost a lot more money than a firing pin retaining pin, so CZ designed the pistol to reduce damage to the firing pin at the expense of the firing pin retaining pin.

Want to know just how far the firing pin can travel forward with nothing in the chamber to stop it?  Remove the slide from the frame and the barrel from the slide.  Use a small punch to push the firing pin forward while using a finger tip to push the firing pin block upwards.  See that?  Hard to believe a firing pin will protrude through that far ain't it.

One time I had an idea (bad one it would have been) that I might remove a firing pin, make the notch for the firing pin retaining pin longer towards the rear and keep the firing pin notch from making contact as the firing pin moved forward.  I did what I described above and the darn firing pin came through almost 1/4". 
I stopped carrying the SIG 556R.  SIG changed models and couple/three times and stopped supporting it with parts.  So, I stopped supporting SIG.  Back to the tried/true AR15 Carbine.

Offline rg422

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Re: Dry firing and the firing pin block
« Reply #4 on: January 15, 2020, 04:34:44 PM »
I think the pin that gets damaged from dry firing is the firing pin retaining pin. It gets the full force of the firing pin when dry firing, not damped by it hitting the primer.

Richard

I broke the firing pin retaining pin on my SP01 dry firing. CZ Custom sells a much stronger version of this part.

Offline NMShooter

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Re: Dry firing and the firing pin block
« Reply #5 on: January 15, 2020, 05:04:20 PM »
I've been using a laser bullet i purchased on Amazon for dry fire practice, hopefully this is cushioning the firing pin sufficiently.

Offline Bench

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Re: Dry firing and the firing pin block
« Reply #6 on: January 15, 2020, 07:36:40 PM »
I've just been so much more at ease using the "O" rings during dry fire.
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Offline himurax13

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Re: Dry firing and the firing pin block
« Reply #7 on: January 16, 2020, 10:53:13 AM »
I cut a used foam earplug in half instead of using o rings.

Offline jurek

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Re: Dry firing and the firing pin block
« Reply #8 on: January 16, 2020, 11:09:00 AM »
M1A4ME did a great job here explaining the issue clearly !!! Thx Bro  8)

I do dry firing a lot... probably more trigger pulls in my P-01 Omega come from dry firing than live firing.
I'm using laser cartridge and CGW FPRP - no single scratch on pin after few months  :)
However laser lives for 2 - 3 months only - firing pin makes nice hole in laser's rubber back  ;D

Offline M1A4ME

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Re: Dry firing and the firing pin block
« Reply #9 on: January 16, 2020, 12:57:23 PM »
Jurek, I bought a used CZ75 Compact for my wife a couple/three years ago (to keep her from confiscating my P09 .40 ::).

In the box with the pistol/papers/magazines was a small bag of odd snap caps.  They had hard rubber inserts (larger diameter than the primer would be) in the back of the snap caps - and another small bag of replacement rubber inserts to replace the worn out ones.

Never saw these for sale anywhere, before or since.

I know the red plastic snap caps (with the bass looking primer insert) get indented pretty deep after awhile.  The hard plastic ones seem to show damage even faster (I don't buy those anymore).

If I did a lot of dry firing I'd seriously be looking at the o-ring in the back of the slide.  I know, doesn't help for the laser practice, but everything seems to be damaged by that firing pin.

I saw a picture of a Glock (on another forum) that had the breechface cracked/busted out from the back end from a couple years of hard use (live and dry firing.)  A couple guys on that forum said they'd seen that happen 5 or 6 times in the past with Glocks.

We complain about replacing a roll pin.  That guy had to buy a new slide.
I stopped carrying the SIG 556R.  SIG changed models and couple/three times and stopped supporting it with parts.  So, I stopped supporting SIG.  Back to the tried/true AR15 Carbine.

Offline jurek

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Re: Dry firing and the firing pin block
« Reply #10 on: January 17, 2020, 09:19:40 AM »
Oh... Glock... ;D Poor Glock :P

I'm using also snap caps with real primer. They have green or orange projectiles (I don't remember their name). They are good for dry firing for few months, then go to garbage with hole in the primer  :)
It's still better to frequently change laser or snap caps than have malfunctioned firearm when it is really needed.  ::)

Offline jnichols2

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Re: Dry firing and the firing pin block
« Reply #11 on: January 17, 2020, 03:51:27 PM »
Thanks for the explanations on how the damage occurs.

I've been using snap caps or o-rings, but never understood why.  ;)

Offline cntrydawwwg

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Re: Dry firing and the firing pin block
« Reply #12 on: January 17, 2020, 08:29:22 PM »
Just an FYI, here’s what could happen. ....... (Unknown dry fires/rounds thru SP01 Tac.)
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Offline NMShooter

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Re: Dry firing and the firing pin block
« Reply #13 on: January 18, 2020, 02:39:27 AM »
I guess I'll have to take the pin out and inspect it to make sure the laser bullet cushions it enough.

Offline jurek

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Re: Dry firing and the firing pin block
« Reply #14 on: January 18, 2020, 11:20:44 AM »
I guess I'll have to take the pin out and inspect it to make sure the laser bullet cushions it enough.

If you are planning to take it out, buy CGW pin before and put that one to the slide.
New one will last way longer.