You're right Dave, I could not find a 6-48 chaser. The drill stop looks like a good idea, I'll look into it. I'm certain I ran the 6-48 tap into another receiver, but it was not SS. As you say Charlie, I was pretty uncomfortable with the process, although it turned out alright. For the Mod12, I cut 17cal patches, stuffed the pieces into the screw holes with a probe, and soaked the patches with Hoppes Elite and Kroil. After a few hours, I screwed a beat up rail screw into the threads and backed it out. The chunky Loctite residue was gone. Viewed through a lighted magnifier, the threads are stained yellow, but there is no residue. As far as tapping the threads for 8-40 screws, I hope I don't ever have to go there! Thanks to all for the feedback.