P-07 Only Firing in SA mode?

[Hammer Time]

Hoping the CZ brain trust can help me out here:

I'm taken P-07s apart multiple times before without issue. The other day, I broke mine down in order to install the CZC Omega DA/SA straight trigger, the CGW extended firing pin/spring and block plunger spring. I also did a bunch of polishing while I was at it. Put it all back together, did multiple function checks, and everything seemed normal - trigger seemed to work fine in both DA and SA, decocker worked normally, snap caps cycled normally, etc.

So today I took it to the range, first time running live ammo through after doing the above, and it would only fire in SA mode. Hammer cocks back and decocks like normal, nothing seems to be different, except it won't fire a round in DA mode at all.

Before I take the whole thing apart again and try to figure out what the issue is, anyone have any tips?

Thanks in advance.

[Tok36]

The first thing that i would check is that the Trigger Bar Spring is in place and the the Trigger Bar is moving freely and not getting hung up on anything.

When you say "won't fire a round in DA mode" do you mean that it is not resetting the DA? Is the hammer moving when you pull the trigger in DA?

[Hammer Time]

The first thing that i would check is that the Trigger Bar Spring is in place and the the Trigger Bar is moving freely and not getting hung up on anything.

When you say "won't fire a round in DA mode" do you mean that it is not resetting the DA? Is the hammer moving when you pull the trigger in DA?

Thanks, Tok. Yeah, the trigger bar spring is in place and trigger bar seems to be moving normally. Hammer moves when I pull the trigger in DA mode. But I took the slide off, and I think I have a little more insight - it appears that in DA, when I pull the trigger, it comes forward, but not fully forward as it does in SA mode. It looks like it just comes back to the decocked position - not fully to the point of connecting with the firing pin. Hope that makes sense.

I wonder if it has something to do with the sear - hammer interaction? But again, there's no issue with the hammer coming fully forward when firing SA.

[Tok36]

   So if i am reading you correctly. When you pull the trigger in DA the hammer moves rearward and then drops to the half cock position instead of dropping all the way down to the Firing Pin. If this is the case it sounds like the disconector is caching on something or the Sear is not being lifted high enough to clear the hammer hooks. It may be possible to closely observe the sears movement during the DA pull to gain more information. If that dose not narrow things down disassembly may be the way to go. Ether way let us know what happens, we all learn from this stuff.

[Hammer Time]

Yup - after looking at the hammer/sear movement more closely, that's exactly what seems to be happening - in DA mode, when I pull the trigger, it is only dropping back into the 'decocked' position, whereas when I pull the trigger in SA, the hammer fully drops. I suspect it's the sear that isn't being lifted high enough to clear the hammer hook, for some reason.

I just took the whole thing apart again this morning and am going to re-assemble. I'll keep you posted... 

[Hammer Time]

Ok, so I took it all apart, put it all back together, and now the hammer seems to be fully dropping in DA....most of the time. It seems like the more I dry fire it since I put it back together, the more it is reliably dropping.

Thoughts on whether going to a heavier sear spring would increase reliability (I'm currently still using the OEM hammer)?

[Tok36]

   The way that i understand it, Sear bounce in the P-Series is not a likely issue with the factory hammer installed. It is more likely with the shorter hammer hooks of the comp hammers. I would consider calling CGW, ill bet they have seen this before.

[CCWLearner]

Did you happen to polish your sear pin this time?

I actually keep a set of almost-new unpolished parts for my P-07's in case I accidentally screw something up while polishing.  I have only needed them once when I over-polished a firing pin block plunger and started having random light strikes due to a timing issue I created for myself.

I'm pretty sure I have an unpolished factory sear pin and one of those CGW sear pins that is supposed to address some rare issue with DA.

https://cajungunworks.com/product/sear-pin-p-07-p-09/

[Hammer Time]

I didn't polish the sear pin, but I'm beginning to wonder if I may have slightly over-polished either the sear or the hammer.

Either way, this was the final push I needed to order what I've been wanting to order for a long time - the CGW P-07 hammer and sear kit. If that doesn't take care of it, I'll order a new sear as well. 

[CCWLearner]

Oh yeah, that may be it then.  I never polished the factory hammers or the CGW hammers I have in the P-07's.  Also never polished the sear.  They both have visible finish wear on them at their contact points.

I run the .020" sear spring and have a crisp SA pull around 3.5 lb which is plenty good for a carry gun... wouldn't want it any lighter than that.  I never bought the .018" spring or the two spring kit because I knew I wanted to get my SA pull up over 3 lb.  I actually put those in before upgrading the hammer, because SA pull was scary light after the other changes I had made.

As far as hammer follow in your case, I never had that problem, but understood it as something that only happens under live fire when your slide is reciprocating, while your problem sounds like it also happens under dry fire.