Scorpion EVO firing pin block defeated

[wyoung]

I'll start by stating that I am in no way trashing the Scorpion or CZ and really hope this issue can be corrected. I love this little gun. I just don't have 100% confidence in firing it very fast right now.

I contacted CZ warranty and support to ask about several recent issues of customers' Scorpion Evos supposedly firing out of battery. The warranty rep. stated they had not received the damaged guns but assured me the firing pin block would prevent the gun firing without the bolt totally closed. Since the hammer can be dropped while out of battery, this is supposed to prevent the firing pin from contacting the cartridge since the firing pin block should stop it.

In my video, I examined the firing pin block and found I only had to move it what seemed like a millimeter or two to disengage it for the firing pin to strike. What's further alarming is I was able to defeat the firing pin block manually with just a brass punch as shown in the video.

I examined the firing pins and blocks of two other semi auto hammer fired pistols I own and noticed their firing pin blocks had to be depressed at least two to four times as far to be disengaged. I also couldn't defeat the firing pin block of either pistol no matter how I tried.

Please check your weapons and let me know if you can defeat your firing pin block.

https://youtu.be/oUHTv55q3JQ

[Buckshot Barry]

I was just looking at the block for the first time while cleaning my Scorpion tonight.

I couldn't see what actually disables the block while firing, could you elaborate on that?

[wyoung]

I was just looking at the block for the first time while cleaning my Scorpion tonight.

I couldn't see what actually disables the block while firing, could you elaborate on that?

There's a lever on the right side of the fire control group that is raised when the trigger is pulled which pushes up on the firing pin block.

[wyoung]

There's a lever on the right side of the fire control group that is raised when the trigger is pulled which pushes up on the firing pin block.

If you can move the firing pin block and allow the firing pin to move, congratulations.   That's how it's supposed to work.

If you can make the firing pin move WITHOUT manipulating the firing pin block, that would be an issue.

That's what my video shows. At certain points I am not touching the plunger just simply pushing on the firing pin with my punch and the firing pin goes through.

[Buckshot Barry]

I was just looking at the block for the first time while cleaning my Scorpion tonight.

I couldn't see what actually disables the block while firing, could you elaborate on that?

There's a lever on the right side of the fire control group that is raised when the trigger is pulled which pushes up on the firing pin block.

I see it now!

Thanks so much

[st381183]

I don't know if you have a problem or not. You're sitting there poking the firing pin with a punch with the bolt upside down which is outside the scope of use for the EVO.  I never shoot my guns upside down ( and yes I know there might be an operational operation where as an operator I might have to operate upside down ).  Poking and manipulating the firing pin and perhaps applying unknown lateral or yawing movement into the firing pin might be binding the firing pin block from resetting in an upside down position could be what's going on here. The firing pin is usually struck by the hammer causing a rapid impulse to drive the firing pin forward and a return spring and inertia return the firing pin back into position.  Sometimes if the firing pin is not allowed to reset properly, as in come fully to rest in the most rearward position then there may be friction or gunk binding the firing pin block from also resetting while in an upside down position.  There is much more "credibility" to the test if you used a fully assembled weapon with a snap cap or primered case in a safe environment to try and induce an OOB discharge.  There are a bunch of guys on this forum who have put many thousands of rounds thru their EVOs with no issue and I'm sure CZ has done countless tests as well.  If you are truly concerned about it then I recommend submitting a work request to CZ CS and reporting back to the group what the results were.

Edit: Also I don't know if the EVO can be fairly compared to a "normal" hammer fired pistol as the EVO pistol is a stockless short barreled pistol caliber rifle that operates on blow back rather than delayed action so there might be some other dynamics taken into account for the large reciprocating mass of the bolt.

[Asmodeus]

His statement is quasi-valid.

It's not that the FPB does not work, it's that it disengages too soon.

I found that to be the case when shimming the FCG to reduce travel.  In doing so I was able to stack the disconnector up to a near miss with the hooks so that it would release the hammer on a pull, and release.  (Binary)  The FPB was still defeated on the release because of how little it needs to be engaged to allow the firing pin to strike the primer. 

I have fairly strong opinions about the FCG in this weapon, and I'm not shy about sharing them.  But this seemed like another afterthought that barely meets the threshold for a FPB.  (It may be more of an inertia blocking drop safety than an actual OOB prevention.)  I was able to insert a small plastic jewelers screwdriver down the bore and launch it on a trigger pull and release from the firing pin strike.  It flew the same distance either way so the FPB wasn't even dragging on the pin during the release.

So this may have literally nothing to do with OOB prevention and everything to do with drop safety.   

[wyoung]

This guy was able to fire an empty, primed shell casing out of battery. He also said his firing pin block can be defeated.

https://youtu.be/S1I5k3_NmGM

[wyoung]

His statement is quasi-valid.

It's not that the FPB does not work, it's that it disengages too soon.

I found that to be the case when shimming the FCG to reduce travel.  In doing so I was able to stack the disconnector up to a near miss with the hooks so that it would release the hammer on a pull, and release.  (Binary)  The FPB was still defeated on the release because of how little it needs to be engaged to allow the firing pin to strike the primer. 

I have fairly strong opinions about the FCG in this weapon, and I'm not shy about sharing them.  But this seemed like another afterthought that barely meets the threshold for a FPB.  (It may be more of an inertia blocking drop safety than an actual OOB prevention.)  I was able to insert a small plastic jewelers screwdriver down the bore and launch it on a trigger pull and release from the firing pin strike.  It flew the same distance either way so the FPB wasn't even dragging on the pin during the release.

So this may have literally nothing to do with OOB prevention and everything to do with drop safety.   

The firing pin block does seem like an afterthought. Also if CZ had made the FPB spring heavier then it would've added to the already heavy trigger pull.

The CZ rep. I spoke to suggested replacing the recoil spring between 10k and 20k rounds. So if you believe the OOB stories being posted where they are supposedly older guns, that may lend credibility to the bolt bounce theory if the recoil spring is too weak. The FPB is so sensitive then perhaps a bolt bounce is enough to disengage it.

The surface of the FPB release is relatively large.

[Asmodeus]

Also if CZ had made the FPB spring heavier then it would've added to the already heavy trigger pull.

Agreed, but there are two ways to skin that cat.  The FPB in a CZ 75 has a drop shelf that snags the shoulder of the firing pin in the models equipped with a FPB.  After it is depressed sufficiently, that catch is displaced out of the path and the FP can travel normally. 

So without adding tension, you could add a longer catch.  And narrow the window to a point in the trigger pull that is further back, or has a smaller disengagement window.

I'm thinking the FPB is disengaged almost instantaneously in the trigger pull.  Granted this does coincide with the position of the bolt group.  But as stated, the contact area is broad.  If we assume this is not a mechanism to prevent OOB fire, then any engagement of the trigger disengaging a drop safety (and preventing any possible no fire malfunction from a errant FPB) makes perfect sense.  If it's intention was that of a more "catch all" traditional FPB, then it appears the FCG isn't the only area the design team slept through...   


I'll be you for a second and say that perhaps, the goal was a bullet proof drop safety for some regulation, contract, or trade deal we are unaware of.  And redesigning it would be too costly etc etc etc.   

 

[st381183]

That video is more convincing to be sure. Has this been replicated with an EVO pistol?

[BisonWorld]

Sounds like a whole lot to do about nothing.

Heck, open bolt blow back autos have been in exsistance for a century now with absolutely nothing preventing a primer from going off should something prevent the round from fully clambering such as an obstruction or out of spec ammunition.

More so a quick Google search will show multitudes of reports of oob firing on 9mm blow back ar15s as well but that doesn't seem to stop more and more manufacturers from offering them each year.

The real crux is that in pretty much every case I can find out there of an out of battery occurring regardless of model of blow back sub gun, it appears that either ammunition was out of spec (A lot of them reported handloads), a squib had occurred on the previous round and another was fired after, or a part failed (some by manufacturing defect and some due to extreme lack of maintenance).

Absent those causes which can and do destroy/damage any and every firearm regardless of design, there doesn't seem to be anything more inherently dangerous here than any other handheld device using controlled explosions to propel things that hurt.

[SouthernScorp]

why do you guys always buy a gun, then google the sh... out of it after purchase trying to find things to complain or worry about?

 Okay so I got this new scorpion here, lets hit the interwebs and see what horror stories are available on it before I clean it and go out and shoot it. Holy crap , a 1 in 100000 chance of an out of battery, omg this gun is garbage I knew I should have spent the extra $600 on the mpx, I'd have gotten better factory support, caliber conversions and reliability for sure.

[Earl Keese]

Truth ^^^

[jmstallard]

why do you guys always buy a gun, then google the sh... out of it after purchase trying to find things to complain or worry about?

 Okay so I got this new scorpion here, lets hit the interwebs and see what horror stories are available on it before I clean it and go out and shoot it. Holy crap , a 1 in 100000 chance of an out of battery, omg this gun is garbage I knew I should have spent the extra $600 on the mpx, I'd have gotten better factory support, caliber conversions and reliability for sure.

Social status. Buying the weapon gets you admission to the group, but developing expertise, or at least the appearance of expertise, gets you a higher rank within the group. Complaining is the easiest way to appear to be an expert. I don't fault the initial testers (generally), who have actually put forth some effort, but the typical ensuing wave of hair-pulling sack riders can get a little ridiculous.