VZ08 trigger and Gremlin fix.

[Airacuda]

My 1st try at help video. Hope you enjoy.
https://www.youtube.com/watch?v=oArqQoDuWMY

[jwc007]

Very very Interesting!    Wondering if that could cause Trigger slap, not that I've had any as yet.

Making this thread a sticky, for the time being.

[RSR]

This was previously covered here (obiwanbonjovi/bonesteel also details the tab dimensions somewhere in the 12 pages): http://www.canadiangunnutz.com/forum/showthread.php/283939-How-to-get-rid-of-the-infamous-CZ-VZ-gremlin?p=4617775&viewfull=1#post4617775

And the why behind the gremlin is expertly covered over here: http://www.ar15.com/forums/t_4_99/145592_Tabbed_bolt_carriers_and_the_vz58_gremlin.html

The problem with the spring tension mod is that it's not a 100% fix due to 1) the increased trigger pull and 2) that hotter ammo or a weakened recoil spring will result in the bolt carrier moving rearward faster and pushing the sear down where the disconnector re-engages the sear and also the trigger spring itself will weaken over time resulting in the gremlin reappearing.

[RSR]

P.S. The gremlin problem -- covered in the AR15 article btw -- is due to the autosear that's been removed from the rifle.  The auto sear ensured that striker stayed rearward until bolt carrier was in battery/all the way forward.  So in semi, both sears are used to grab striker until the bolt carrier was in battery.  That disengages the auto sear, which then meant just the trigger pull to disengage the semi sear to releases the striker.

http://youtu.be/oQMh85CnCZE

Here's the actual time stamp for sears: http://youtu.be/oQMh85CnCZE?t=10m

While high level, you have two springs on the Century model and spring adjustment does similar.  The spring tension alone cannot always fix the now single semi auto sear being pushed down so far that it re-engages the disconnector, allowing the striker forward.  Only the tab is a 100% fix, since it re-releases the disconnector before the striker again crosses the sear.

[Varickm]

Very very Interesting!    Wondering if that could cause Trigger slap, not that I've had any as yet.

Making this thread a sticky, for the time being.

I've experienced a similar issue with the rarely discussed Ohio Ordnance VZ2000.  I wouldn't consider it trigger slap because when firing, you don't feel it. But when hand cycling, you do feel it......When moving forward, the bolt carrier pushes the disconnector forward (then down), instead of just pushing it down. This causes the striker to drop..........For me, the problem  was the radius of the "OOW" marked disconnector.Therefore, I am hesitant to trust CAI and OOW fcg parts....... VZ parts do wear and FCG tolerances are pretty tight...... Like "RSR" said, the only true fix is to tab the bolt carrier....I truly believe the VZ design is superior to the AK design. But when it comes to the FCG tolerances, the VZ can't compete with the AK. In other words, find a reliable FCG- problem solved!.... It's your VZ's only weakness.
......
There is also another problem that I encounter....The sear can walk to one side of the pin after a few pulls of the trigger, causing the disconnector to shift off the sear when the trigger is pulled, instead of pulling it down to drop the striker....The issue is caused by side to side movement of the trigger and sear. I've personally seen it twice. Both times, it was the cnc warrior FCG in Czechpoint rifles. It can easily be fixed by adding a shim to the pins, minimizing the side to side movement......Both times, the striker had to be released by pushing the base of the trigger towards one side, in order to remove the dustcover.

[RSR]

*FWIW -- Not a weakness in the original full auto configuration!

Just the aftermarket setup...

And the wide sears are superior to the narrow ones.

E clips or some folks use 22 lr brass shell casings (there's a youtube) to make a shim for the 2nd issue.

[CitizenPete]

I've experienced a similar issue with the rarely discussed Ohio Ordnance VZ2000.  I wouldn't consider it trigger slap because when firing, you don't feel it. But when hand cycling, you do feel it......When moving forward, the bolt carrier pushes the disconnector forward (then down), instead of just pushing it down. This causes the striker to drop..........For me, the problem  was the radius of the "OOW" marked disconnector.Therefore, I am hesitant to trust CAI and OOW fcg parts.......

Glad you posted this on the OOW (Ohio Ordnance Works, Inc.) MDL.VZ2000 VZ58 FCG (Fire Control Group).  I had sent OOW an email on this topic a few days ago in an attempt to implement a fix proactively (having several of the OOW VZ.58 variant).  No reply as of yet.    However, I have NOT seen any post online indicating the gremlin problem crops up on the OOW VZ2000 semi-auto VZ58 variant.   I am no expert on these things, but the OOW VZ2000 receiver milled internals and their FCG appear to be different from the CAI and SA (CSA) FCGs.   Also, OOW did NOT include the tab on the bolt carrier.

I do actually remember one fellow at OOW saying something about how the VZ2000 was different from other variants because of the trigger problem others experienced, but not being aware of the gremlin issue, it did not mean anything to me at the time.

Has anyone ever experienced, or heard of, the OOW VZ58 developing the gremlin problem?  I can not find any post online that confirms the problem exists.  Did OOW get it right without the welded tab? What is the "Patent Pending" on the OOW MDL.VZ2000 Receiver for, and who filed it (or, who manufactured the VZ2000 receiver for OOW)?

Here is a 2006 (CZ) US Patent for the VZ.58 Auto to Semi Conversion FGC:  Patent Abstract and Image  http://pdfpiw.uspto.gov/.piw?Docid=07676974&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO2%2526Sect2%3DHITOFF%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsearch-adv.htm%2526r%3D1%2526p%3D1%2526f%3DG%2526l%3D50%2526d%3DPTXT%2526S1%3D%28VZ.58%252BAND%252BReceiver%29%2526OS%3DVZ.58%252BAND%252BReceiver%2526RS%3D%28VZ.58%252BAND%252BReceiver%29&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page

and full patent...

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=1&p=1&f=G&l=50&d=PTXT&S1=%28VZ.58+AND+Receiver%29&OS=VZ.58+AND+Receiver&RS=%28VZ.58+AND+Receiver%29

[dernt]

This was previously covered here (obiwanbonjovi/bonesteel also details the tab dimensions somewhere in the 12 pages): http://www.canadiangunnutz.com/forum/showthread.php/283939-How-to-get-rid-of-the-infamous-CZ-VZ-gremlin?p=4617775&viewfull=1#post4617775

Could that be reposted here?  I followed the link, but I have to be a member of that forum to read the message.  I am especially interested in the tab dimensions and material.  Is plain low carbon steel going to do the trick? 

[dernt]

I registered at candiangunnutz and skimmed all 13 pages in that thread.  Didn't see obiwanbonjovi post with tab dimensions.

[CitizenPete]

Had 2 striker resets (gremlin) during range time : 200 some rounds.  With tabbed carrier.

[TJNewton]

Had 2 striker resets (gremlin) during range time : 200 some rounds.  With tabbed carrier.

I think that your post was clear, but I just want to clarify: 

Did you pull the trigger, hear a click but no fire, then racking the gun solved the problem? (striker not catching and following the bolt into battery)

Or did you pull the trigger, feel no resistance and hear no click, but playing with the safety selector solved the problem? (safety selector or other part of FCG walking out)

Thanks for any clarification as I just got my carrier tabbed.

[foxfyre841]

I believe this is also called the hermex effect.  VZ58rifle.com has something that looks to be designed to alleviate a second trigger/disconnector slap on the return stroke. 
http://www.vz58rifle.com/products/modifikovany-prerusovac-spouste-pro-cz858-a-sa-58/
http://rozpad.cz/forum/download/file.php?id=1703&t=1
http://rozpad.cz/forum/download/file.php?id=1515

However, this looks like it will only work on a double-pull gremlin?
e.g.: It will not work on a 'gremlin' stemming from the striker push-down of the sear such that the sear-foot rotates forward of the disconnector protrusion which can be exacerbated by wear (less likely) or a partial release of the trigger prior to the carrier group's initial contacts with the sear and disconnector.


Tabbing is still the best solution.  Though ORF's old compliance package came with a forked extended disconnector intended to interact with the standard carrier nub. However, I hate that the foot on the sear became a rollpin.
http://1919a4.com/showthread.php?16432-VZ-58-build

[RSR]

foxfyre841 -- thanks for sharing.

Yes, it looks like the extended disconnector accomplishes the same effect as the tab, but it does on the disconnector side rather than the carrier.  Interesting nonetheless.  Haven't seen the ORF parts before, very cool.

The VZ58rifle.com part, I think due to the pivoting disconnector it functions similarly due to the pivoting upward portion of the disconnector -- increases the range/length of interaction between the carrier and disconnector just like the tab and the ORF disconnector do. 

The Hermex effect is what the tab and the ORF part attempt to rectify, as does the VZ58rifle.com part as well. 

The other issue mentioned by the VZ58 site is the side to side play that results in you sometimes needing to pull the trigger twice to release the striker when using the original trigger group and semi auto sear only -- e.g., the small sear in your photo not the wider one as utilized by bonesteel and century.   Somewhere there's a video out of Canada of them using the base of a 22lr casing as a spacer on the sear pin to accomplish the same (looks like the VZ58rifle disconnector prohibits the sear from that lateral movement).

In full auto, both the left (from shooter perspective: narrower, semi auto) and right (wider, full auto) sears catch the striker in semi auto (due to full auto mechanism, the full auto striker releases automatically when bolt carrier is in batter, allowing the trigger pull to release the semi auto sear once pulled).  Full auto, just the full auto catches the striker when the trigger is released.  As the semi auto sear was never intended to arrest the striker on its own and is more delicate than the full auto sear, conceptually the semi auto sear is a potential failure point.  Whether that is actually a problem, I don't know -- but something to be mindful of.  Again, the bonesteel or Century trigger group with the wide sear should make this sear failure null and void.

[losingle]

Finally an answer I can understand. I bought my vz2008  a couple of months ago an after 600 rnds at the range with no failures, I was trying to figure out how the trigger gremlin could happen. The pics showed a sear that I did not have on my rifle.  I can't see a need for tab on a 3rd gen. cia.

[RSR]

Finally an answer I can understand. I bought my vz2008  a couple of months ago an after 600 rnds at the range with no failures, I was trying to figure out how the trigger gremlin could happen. The pics showed a sear that I did not have on my rifle.  I can't see a need for tab on a 3rd gen. cia.

What's your trigger weight?  As those trigger springs lighten pressure, it's more likely for the gremlin to appear.  As is running hotter ammo like Golden Tiger over lower pressure ammo like Tula...  Essentially it's a timing issue and the tab ensures the disconnector is reset (not holding the sear down) allowing the striker to move all the way forward without being caught by the striker...