This invention concerns a device for a weapon sight. The device includes a deflecting element (15) disposed in an optical path through the sight and comprising an optical wedge (17), and means (16) arranged to control the positional setting of the optical wedge to produce a randomly altered sight image in the sight. The device is characterized in that the control means (16) are arranged to produce, before firing, the altered sight image and, during firing, to guide the wedge or wedges to a reference position in which the sight image is unaltered. The invention also concerns a method for optically simulating recoil in a weapon with a sight.