I have a 15 + year old set of Ruger brand, colored plastic front sights for my regular Redhawk. Go on to the Ruger sight and go to sights. It should cost about $15.00 + shipping.
Take a small screwdriver or a punch and press on the pin under the barrel The sight should lift out. If that does not work, E-Mail Ruger and or download their Instruction Manual for the gun and caliber you have.