Thank you for your response! I remember seeing an adjustable reamer set at the local Harbor Freight store for about sixty bucks back when I was laboring on the mag tube sleeve removal. I wish now I had popped for it, but instead I just soldiered on with the sanding barrel, which eventually worked, but was way too much work in retrospect. Lesson learned, though I doubt I'll need to do this ever again, as the Rhodesian A9s seem to be going for about 3.5 kilobucks a throw now, way out of my league. Take care, best of fortune to you with your restored Rhodie scattergun!