Borescope pics- anybody guess what this is?

[nvtoy]

I think it’s premature to blame moly. Was just on another site that showed a barrel with the same pattern of pitting w/o moly use. Amazing how some people criticize the use of a bore scope, wouldn’t be without one. It can save barrels from getting to this point if you use it. MHO

 

[DickE]

Starting to look like an epidemic. I've never seen this before.