My Ruger GP100 has their interchangeable front sight system. HiViz makes a drop in sight that fits the Ruger. The light pipes are available in a little tube with a rotating top to select the color you want, and quickly interchangeable without damaging the pipe. I have two front sight units... one set up with red for outdoors and one with green for indoors. Been using them for five years and LOVE 'EM! Swapping front sights takes seconds and the POI doesn't change.

Chris Christian A23489   former SO 
Arguing with a fool is like rolling around in the mud with a pig. You both get filthy dirty, but the pig enjoys it.