CZ 75B SAO not working

[texas yankee]

I replaced the stock SA\DA trigger with a SAO trigger a while ago - my SAO trigger has one adjustment screw on the face of the trigger and another one ya get to from the top of the trigger with the slide off - at that time I also removed the disconnector and the firing pin plunger and put in a spacer - all worked fine until yesterday at the range, when the hammer wouldn't drop when I pulled the trigger after racking the slide - at the range, I tried manually pulling back on the trigger a bit  (like firing a revolver in SA) - I heard a slight click, and when I pulled the trigger again the hammer dropped and the round fired.  I thought that maybe one of the trigger adjustment screws moved so I took the gun apart today to put some loctite on the screws and finally got it all back together - getting that trigger spring back in with the slave pin was difficult - but still no love on the gun working properly, dropping the hammer when I pull the trigger.

With the slide off when I manually cock the hammer and then pull the trigger, the hammer drops - but the hammer won't drop when I rack the slide (cocking the hammer) and then pull the hammer.  I'm guessing that the problem has nothing to do with the adjustment screws - any suggestions?

[Tok36]

I would closely observe the Sear while pulling the Trigger. It is visible with the hammer fully cocked. The Sear sits on a pin within the Sear Cage and lifts up like a paddle when pulling the Trigger. If the Sear is able to lift up high enough, it clears the Hammer hooks and the Hammer drops.

Check the Trigger Bar Spring position on each side of the Trigger bar to ensure that each leg of it is providing up tension to the Trigger Bar. The Trigger Bar directly pushes on the Lower leg of the Sear. If the Trigger Bar dose not have enough up tension it can fail to engage an actuate the Sear properly.

[Lock-n-load]

I agree with Tok ,check trigger bar spring adjustment.he had some good directions a while ago.

[tdogg]

I'm going to guess that the trigger screws are set too tight.   You want to ensure that there is play such that when things get dirty or warmed up there isn't interference.

How to Adjust Trigger Screws:
https://cdn1.cajungunworks.com/wp-content/uploads/2020/07/28155351/How-To-Adjusting-Trigger-Screws.pdf

Cheers,
Toby

[texas yankee]

Thanks for the suggestions - I backed out both of the trigger screws.

I can see the two arms of the trigger bar spring up against the underside of the trigger bar. 

I tried to follow TOK36s suggestion about watching the trigger bar, but I really didn't see either one of the humps in the trigger bar "jump". 

Scenario #1 - After racking the slide (and then taking it off), I don't see any movement of the sear with the hammer cocked when I pull the trigger - BUT if I rack the slide and then remove it, and put a VERY slight bit of rearward pressure on the hammer, that rearward pressure on the hammer causes the trigger bar to pop up, and then pulling the trigger causes the hammer to drop as expected.
 
Scenario #2 - With the slide off, when I manually cock the hammer, I see the sear move, and then when I pull the trigger the hammer drops.

I guess that for some reason the trigger bar NOT interacting with the sear?  Any suggestions ??

[Tok36]

Lets eliminate some variables. If the Trigger Set screws are still installed, i would remove both of them completely and see if this influences the pistols behavior. 

[texas yankee]

TOK36, YOU DA MAN!!! !!!  I removed the set screw from the front of the trigger face (over-travel ?), and then went after the screw that ya access from the top of the frame with the slide off (pre-travel ?) - I couldn't get the screw all the way out because that front piece of the trigger bar, where it connects to the trigger, didn't give the set screw enough clearance to come all the way out, and apparently when the screw was as far out as I could get it, it was inhibiting the front piece of the trigger bar from moving freely, because as I was turning the screw in a little bit, I heard a "pop" or a "snap", and even I think I saw the trigger bar move just a bit - I put the slide on, racked it, and the trigger dropped the hammer just like it should - oh yeah, it worked as it should.  I have a bad case of ADHD, and I find it difficult to walk away from something that I can't get working correctly - after wrestling with that trigger pin and trigger spring and slave pin most of last night, and beating up the ends of my fingers, AND using up all my swear words, man, I'm gonna sleep good tonight!  I'm gonna try and tackle the other set screw (over-travel) tomorrow, and I'll post some measurements about the trigger travel on my CZ, too.  I'm a happy guy - thanks for all of the help - much appreciated !!!

[Tok36]

Glad to hear that you got it working. It looks like Toby caught this one before i did when he posted above. I will quote his post here so that you can follow the PDF from Cajun Gun Works that he linked. It is a good guide for adjusting Trigger set screws. The general gist here is that you need to leave some extra play for the Trigger in both directions for proper long term function.

I'm going to guess that the trigger screws are set too tight.   You want to ensure that there is play such that when things get dirty or warmed up there isn't interference.

How to Adjust Trigger Screws:
https://cdn1.cajungunworks.com/wp-content/uploads/2020/07/28155351/How-To-Adjusting-Trigger-Screws.pdf

Cheers,
Toby

May your CZ run flawlessly.

[texas yankee]

Yep, absolutely Toby had it right, too - it was the screws - Thanks very much Toby!  You da man, also!!! I must have missed your post as I was getting more and more pissed at the gun - I’m very grateful that all you guys took the time to share your experiences with me and help me.  Now I gotta find someone to help with something - LOL, I would have never guessed that it was those screws - so much for my firearm diagnostic capabilities !!

[texas yankee]

One other quick question - while the gun seems to be working fine in SAO, I wanted to get the pre-travel screw out to apply some thread locker and I found that the screw was being prevented from coming out all the way by the front part of the trigger bar - is this normal behavior?  I'd like to apply the thread locker, but taking the trigger bar and trigger apart and getting frustrated again with that trigger spring when I'm putting it all back together isn't appealing - and chances are that the thread locker will start setting up before I get the parts back together and can adjust the screw correctly.  Any suggestions ??

[Tok36]

   I do not have a 75 variant in SAO configuration handy to look at at the moment. If i remember correctly. With the overtravle set scerw backed out or removed, i believe that pulling the trigger all the way back, then driving the SA pretravle set screw forward may allow you to apply loctite to the set screw threads with a toothpick. Then back it in to where you want it.