cl_crosshair_outlinethickness <number>
Sets the thickness of the crosshair outline. Range is 0 to 3. The outline is only drawn when cl_crosshair_drawoutline is true.
Examples
cl_crosshair_outlinethickness 1 - Default outline thickness.
cl_crosshair_outlinethickness 0 - No outline.
cl_crosshair_outlinethickness 3 - Thickest outline.