I had the most trouble determining where to set the trigger stop in the process. what does that screw really do and why won't the trigger pull if the screw is set too tight?
You want to set this screw so that it stops the trigger right after it breaks. To simplify the explaination, the overtravel screw is simply a jam screw that stops the rearward motion of the trigger. If you set it too deep, it will stop the trigger motion before the trigger is allowed to be pulled far enough back for the sear to release. Removing overtravel helps to remove any added movement that the gun might make at the moment that it is fired.