Concerning mods for the P-O7 P-O9 this was given to me by "s0nspark".
He didn't mind me passing this along before so here it is :
Ok - here is the rundown... just as an FYI, this is generally geared around the P-07/P09 series but the general idea applies to almost every CZ - the specific part options may just differ
As discussed in the thread, the two weak points, historically, with CZs has been the trigger return spring, the firing pin retaining pin and the slide stop. Generally, if something has broken on a stock gun it is one of those parts (and, of course, the slide stop usually only fails after suffering a ton of rounds through the gun...)
I would replace the retaining pin and the trigger return spring with the ones from Cajun Gun Works at a minimum. It has been suggested that CZ went through a period where the TRS materials they sourced were somehow out of spec and that is what caused the unexpected breakages. Many folks don't bother replacing the stock part - they just make sure they keep a spare or 2 handy. I prefer to play it safer... the CGW parts are better parts to begin with. The slide stop is usually only a concern as your round count rises but, again, I choose to keep a spare on hand to minimize down time if one breaks.
As for the other upgrades, for the P-07/P-09 series they improve either the double action or single action trigger press.
Out of the box I find the DA press rather heavy on most CZs and sometimes it is not very smooth - the Omega triggers do seem better in this regard, but the issues are still there. To address them you would do the following things:
1) Replace the stock 20# hammer spring (HS) with an 18# (defensive use) or a 15# (competition/range use) CGW spring- this lowers the DA pull weight. Actually, using the CGW TRS reduces the DA weight by about 1/2# too. You would opt for the 15# HS only for competition use, really, because it limits your ammo choices and generally is better suited to those who reload and can choose softer primers.
2) Replacing the HS requires you to, at least, replace the FP spring as well because a lighter hammer spring reduces the amount of force the hammer strikes the FP with and, if you pair that with the stock FP spring, you run the risk of light strikes.
3) I also replace the stock FP with the CGW extended FP in my defensive guns, just to make sure the gun goes bang when it should. This is not strictly necessary, though, for range use.
4) Another small upgrade that helps to smooth out the DA press is the firing pin block plunger spring - this is a reduced power spring that does not affect function but reduces the feel of disabling the block during the trigger press.
5) The final component of the DA upgrade parts is the roller - the stock roller sometimes results in a less than smooth trigger press and timing issues. The CGW part addresses all of this.
The SA out of the box is not as crisp as it could be and there is a bit of creep there usually. The reset is also not as short as it could be. To address that you would do the following:
1) Replace the hammer. The CGW hammer (or the CZ Custom hammer) changes the geometry and allows for a super crisp break with no creep and very little, if any, overtravel.
2) Replace the trigger. CGW makes an trigger with an adjustable overtravel screw - this will allow you to totally eliminate any overtravel.
3) install the CGW short reset kit. This actually includes the FP and FP spring as well as a better quality lifter and disconnector. The lifter and disconnector and tuned to reduce the reset point by 40-50%.
4) if you find that the SA trigger is lighter than yu would like after these upgrades you can swap in a heavier sear spring - there are basically 2 heavier options, depending on how much heavier you want to go.
Upgrades for other CZs follow similar a path - there are a few more options available there, though - more hammer spring weights, etc... There is also a reach reduction kit available for those guns that can help if you find the DA trigger position to be too far out there. Another option is CZ Custom's flat trigger - it has a cool shape and, again, reduces the trigger reach. Sadly my fingers are too long to even consider that.
I know this is a lot to take in... don't let it overwhelm you
A lot of it comes down to how you intend to use the gun. Just know you have options to tune it as much as you may like.
Also using the, joemustang99 videos on YouTube for disassembly reassembly of the PO 7, po9 those are invaluable.
