Gerard
Point taken about channeling heat away. Perhaps if we go the other way round where the monos may actually absorb more heat from the combustion and then pass this through the barrel wall via the point of contact, the lands. I know it's a long shot but if this OSR has not been dimensionally measured or even able to be 'felt' then, as you say, it may be of no consequence to the operation of the rifle and may only be a visual distraction to the finish of the barrels.

There seems to be various theories put forward as to how the rifling engraving could be pushed out and show as a surface disruption on the outside of the barrel, if it is indeed a physical disruption as such. I would be interested to know if anyone who has seen this phenomenon has actually measured it or if it is able to be 'felt'by touch. Some have placed great store on how the human eye can see imperfections that are difficult to photograph, but we should acknowledge that the human touch is also very sensitive and can pick up imperfections in the surface of objects. Has anyone done this with OSR? Again if not then maybe that's all we are looking at - a visual imperfection in the surface colour and nothing else?