Well sort of, there are Many ways to remove metal from the bore and a Sunnen hone would be great but as you said, it is not something most gunsmiths have. There are other ways though. The lead lap has been used for this purpose as long as gunsmiths have honed bores. There is a system that Dennis Potter showed me where he had modified Sunnen parts so they can be driven by a hand drill, genius and it works. I use backbore reamers. I'm sure others have other techniques. I recently cleaned up a set for a client that were .722 and deeply pitted, they really looked bad. We ran the .730" reamer down them and adjusted the chokes afterward. Not perfect but damn close and we still had over .030" walls in the end.
Steve, what is the most you have had to take out to clean up a set of barrels that were deeply pitted? In this case it was .008 but have you had to go larger than that? What do use for minimum wall thickness and at what point in the bore?
