Williams I know, and maybe Lyman,make some excellect bolt on receiver sight, with "fiber-optic" reticles. My experience with XS sights as an LEO was not good. They did not give a precise sight picture for what we needed. The local SO SWAT ditched them. My Marlin 1894 .357 and Ruger .44 Mag Carbine both wear Williams sights. Another rifle I worked on also uses Williams fiber-opic sights on a .35 Rem lever action. There are also reciever sights, available to fit pe-drilled slots on your actions, that are scary-accurate. Check some google-based searches on what you want.