I have several Bianchi 9R holsters with a Chicago Screw in each. When they are tight, a screw driver only turns the rounded back head.
Is there an easy way to loosen Chicago Screws?
Usually, finger pressure upon the rounded/back part (also called the nut ) will do the trick. You know...just press down on it with your finger or thumb, kinda holding it in place while turning the screwdriver?
Unless it's really torqued down, which it really shouldn't be.
A small piece of tape (scotch, duct or adhesive tape will work) placed to cover the smooth side of the chicago screw, and held there with your thumb, will facilitate the removal of a tight chicago screw.