The trigger bar spring is not the first place people usually look to reduce the trigger pull weight on a CZ 75 series. In fact, I'm not aware of any other offerings, apart from the Eemann Tech's Competition Trigger Bar Spring which is the subject of this quick review. People have played around with bending this spring though, especially on the P-series' Omega trigger system, so it is not entirely left-field.
The trigger bar spring pushes the trigger bar upwards in order for it to engage the sear or disconnector on the single-action or double-action trigger pulls respectively. As you can imagine, the trigger bar runs mostly forwards and backwards (except for a small bit right at the back of the trigger stroke, where it dips downwards to release the double-action shot.) Since the trigger doesn't compress this spring directly, a lighter spring will not have a proportional impact on trigger weight. It will reduce friction though, which raises the opportunity for some other benefits.
The animation below (credit unknown) misses a small detail on the trigger reset mechanism, but it is close enough to illustrate the movement of the trigger bar (light blue.) You can see that the trigger bar transitions from moving straight rearwards to slightly downwards just before the breakpoint, against the pressure of the trigger bar spring. Without going into detail, this downwards travel is also why a lighter gauge spring would allow more consistent pressure than bending the standard spring.
It is important to note that my test setup includes a single action trigger, which limits the trigger bar's range of movement significantly. A double-action pistol may experience more pronounced benefits, but will also be more demanding in terms of reliability. Despite having fired thousands of reliable rounds using lighter hammer springs, I have finally settled on an 11lb version and competition trigger return spring. I am attracted to this combination because it gives me a more defined "final wall" which makes it easier for me to prepare the trigger at speed. Heavier hammer springs also tend to support a cleaner break by increasing the static friction threshold (stiction) between the hammer and the sear.
My preferred setup should give a clear indication that I am more interested in the quality of the trigger pull than by the quest for ultimate lightness. This is why I was intrigued by the Eemann Tech competition trigger bar spring - it modifies different aspects of the trigger stroke than the usual upgrades. What I found was exactly that.
The most noticeable difference was on the return stroke. The competition trigger spring tends to make this stroke a bit sluggish, much to the dismay of some shooters. By reducing the friction inside the pistol, the competition trigger bar spring renders a more positive, cleaner return stroke. As could be expected, I found the reset to be slightly “softer”, though. This is of no consequence to me, as I do not "ride the reset", but there will be shooters who disagree.
On the pull stroke, the weight difference did not jump out at me. If anything, it is more noticeable on the pre-travel than on the total (breaking) weight. I liked this. It allows me to reduce the total trigger weight without sacrificing the quality of the "wall". Shooters who manipulate the trigger differently may find it much of a muchness, though.
Overall, the trigger was a bit smoother although I didn't have any complaints about my well-run-in pistol before the upgrade. It should also be more noticeable on a double-action gun than over the short movement of my single-action only pistol, though.
I did not measure the overall weight difference. My test mule is not exactly standard, so the results would not be typical. Eemann claims roughly 200g, which is about the same as going 1lb down in hammer spring weight.
In conclusion, any opportunity to shave off grams away from the main compromise on a CZ (light strikes) is always welcomed, and this one brings some additional benefits. Any possible trade-offs will be on the reliability side. There will always be early adopters, so we will soon see whether this upgrade will turn mainstream or be reserved for specialist applications. If it does turn mainstream, I believe that it will be in a support role - to balance a pistol that has been made light in all other areas.
It is important to note that the installation cost / effort far outweighs the R75 cost of the part, so whether you want to be an early adopter, or not, will be determined by how comfortable you are with working on your pistol. Or how close you are to your gunsmith. The trigger bar spring is located deep inside the pistol, one step beyond the trigger spring in the disassembly process. It should also be installed with particular care, to ensure that the spring is not twisted when the screw is tightened and that the horns run centred in the channels on the trigger bar. If you don't find this daunting, and a lot of people won't - go for it.