Hello all, just an update for future searchers. There are 2 ways to skin this cat. One is mill thru the trigger face at an angle. You can start with a .100 end mill for good results, then finish to final size. A 3mm set screw is correct or a 6-32 will do. The factory hole for overtravel is 3mm. so I recommend 3mm on pre as well. Some local hardware stores will have the 6-32, but not the 3mm x.5 pitch needed, which is why I mention both.
Another method, is to flip the trigger and use a drill press from the back side. You will find that the inside of the trigger is angled in such a way, that when drilling a set screw, it will provide the correct angle when drilling straight down. Just be sure to be careful and project it's patch, so it is in the right place when it comes thru the trigger face.
All in all, just paying one of our great suppliers 30 dollars is probably the best method, unless you see this as a hobby, or your time has no real value. The trigger is 9 dollars, then if you buy an end mill you are near 30 for that, so you are at 39, then a tap for 4 or 5 dollars, then a set screw for .50. So if everything goes well you are at 43.50.
Now, you can drill, so a number drill bit ( based on which tap you will use) is 3 dollars, then a tap 4 dollars, then a set screw, brings the total to about 16.50 plus say an hour of time ( measurements, drilling, tapping and so on. If you make a mistake, each time the cost goes up by 9 dollars and shipping.
This is why I say it is best to pay the 30 dollars to our suppliers. If you have all the tools and equipment, you may, (like me) view it differently.
Now for the usefulness. On my 75B SS, the SA trigger exhibits some pre-travel, but almost no over-travel, even without an over travel screw installed. The over travel is almost concerning, as I am trying to determine if it lifts the sear enough to fully clear the hooks. It is close for sure. To add a hair more over travel, you would need to file or sand the rear of the trigger where it hits the frame. This can be the tolerance of my particular gun, but that is how it is working out. No perceivable over travel even without the set screw installed.
The pre travel screw, as it is currently, only offers a little adjustment before the trigger will not reset. So as a standard 75B, you can't use it to eliminate pre-travel. Again, this is on my specific 75B SS, which I do believe is all over spec wise.
You can use it to slightly reduce pre travel.
My next move is to install the FPB spacer, and eliminate this feature, just to see how much adjustment can be had at that point. I use this gun as a Kadet often, so if removing the FPB allows me to remove almost or all pre-travel, I may keep it as a dedicated Kadet. If not, then I see little value to the SAO only trigger. Keep in mind, the trigger I use prior to the SA, is the CGW old style 85c trigger, in which the curve is greatly reduced to almost a "target" type trigger.
Also, as a side note, the SAO trigger itself from CZ is not the same quality as the standard trigger. Looking at the top where the trigger pin goes thru, and the trigger bar rides, and comparing this to a factory steel trigger, you will see what I mean. It appears to be a 2 dollar part that was painted flat black. 9 dollars is probably more than it is worth. It is the first time I felt a CZ part was not of robust design.
I will report back
Thank you
Rich
