Thought provoking point Mike, but I think that link just notes that the center line of the two bores converge at some point or another in the muzzle direction. It doesn't seem to show if there is any curve in the bore between the breech and muzzle. I'd still suspect the point where a gun bore sights to and where it patterns is probably different, and maybe it should be patterned with a hold that's similar to how it will be used.