jdgray,
I agree, I have never understood why CZ-UB includes a bushing wrench for the screw in bushing. If, somehow you manage to get the threads tight, the flange will probably crack/break since this a potential stress riser area.
Plus, the bushings ID is still sloppy. The design is fine for a service grade pistol, but there is an accuracy goldmine to be had when you get the muzzle stabilized.