No JabaliHunter that was exactly my point of using the analogy with a UFO sighting, just because OSR is visible it does not follow that it is a measurable phenomenon in the physical sense with some form of caliper, gauge etc. If OSR is not actually a physical displacement of metal but only a change in appearance of the metal finish, caused as in the theory I put forward, by heat, then this is only a visual phenomenon and while ‘measurable’ in the aesthetics and possible degradation of the value of the rifle (a consequence you so rightly pointed out), the OSR would not necessarily affect the performance or safety of the rifle in question.

I am only thinking outside the square, not saying that OSR is, or is not, a physical change with metal being displaced on the barrel. It just seems to me at the moment there is a whole lot of assumptions and accusations being made based on a visual appearance of some double rifle barrels, unless as I said earlier I have missed a post where someone has actually measured a displacement of metal or can actually feel the displacement of metal by running their finger over the surface.

If my theory was proved correct then it is maybe something owners of doubles would have to put up with if wanting to, or having to, use mono bullets.

Of course there is the other issue which has been bought into the argument, and that is the top and bottom ribs and other fixtures coming ‘unstuck’ on the barrels. I don’t think this issue is necessarily new though and have even seen it myself on old shotguns. Again it is easy to make assumptions even here such as proposing the modern loadings of hard lead or steel shot and plastic wads, could be the cause of a greater occurrence of this happening (if indeed there were greater occurrences happening , I don’t know).