I have trouble with the factory sights on Ruger Single Actions so I fill the serations on the front sight with gold, white, or silver paint. I use a paint pen from the drugstore. Just color in the sight and wipe away the excess right then. This leaves paint in the serations, but not on the top of the ridges. Any mess can be rubbed away with a rag and oil. The effect is a light colored sight against a dark background and a dark sight against a light background.
