I bought a ruger gp100 with a 6 inch barrel a few years ago, I now want to mount a red dot on it but can not find a mount that replaces the back sight only. I want to mount something like a burris fast fire on it. Is there a mount that just replaces the back sight ? All the mounts I have found so far run the entire length of the pistol and honestly are quite ugly. I was about to put it up for sale till I found this forum and figured I ask here before trying to sell it.