Is OSR visible when the barrels are wiped clean of any oil or residual film?

So, just how much of an issue is this if you can barely see it, may not be able to measure it, and it has no effect on accuracy or regulation?
Sounds like a big to do about nothing.

Also, before sounding off about loose ribs and such, remember that loose ribs happen fairly frequently on SXS shotguns too and I hasten to think that the causes in shotguns are largely the same in rifles. Ribs have been loosening since ribs have existed.

Personally, if I had a set of barrels with OSR, I would see it as an opportunity to have the gun reregulated to a modern powder/bullet combination.