Rogue555

Well, that depends on which rear sight you have.... A Williams ramp sight or a TC hunting sight.

Z5's usually have the Williams ramp sight. You have loosen the side elevation screw and slide the sight off the ramp. That will expose the screws that hold the ramp to the barrel.

TC - sigth - remove the elevation screw on top flip the sight forward and remove the screws from the base.

That should do it - give a shout if I missed something...