Mount assemblies for securing laser sights (designators) to a wide variety of guns through mounting of the designator directly to an existing conventional scope. The mount assembly includes a base adapted for attaching the mount assembly to a scope, a rail pivotally attached to the base, and a ring assembly on the rail for mounting the designator to the rail. A first adjustment mechanism is provided for pivoting the rail in a first plane toward and away from the base to effect elevation changes in the trajectory of a laser beam generated by the designator, and a second adjustment mechanism is provided for pivoting the rail relative to the base in a second plane to effect windage changes in the trajectory of the laser beam.