Keith Kearcher mentioned polishing the threads on Lefever compensating screws to get them to run in a little bit deeper to get more adjustment. I've measured a few of these screws on Syracuse Lefever guns, and one of the later D.M. Lefever crossbolt guns. They are a non-standard bastard thread, and they have a slight taper which limits the travel available to put an off the face gun back on face. The compensating screw does no good to tighten loose bolting. The bolt is relatively simple to make, so just making a slightly thicker bolt is as easy as trying to build it up with welding. And sometimes you see one that was tightened by some jackass who peened the notch in the rib extension. Lefever guns are top bolted only.
I'd think trying to build up the hemispherical face of a Lefever compensating screw with any kind of weld, and then machining the hemispherical face correctly would be quite a feat.
