I have 4 Rock River Uppers.
1 from Adco purchased December of 2003 and 3 from Eagle Arms all purchased in September.
All 4 have the mark like the one the Mongo posted.
Interestingly, 2 of them have a 'normal' counter bored muzzle, and 2 have kind of a convex muzzle crown.
I know that when I ordered 3 from Eagle that he said he had 1 in stock and he had to order 2 more. My guess is that the convex bbl change is new
However I am off topic, sorry, the marks on all 4 are like Mongos, and thus far, not flaking of any sort. Does anyone have a manufacture time frame for the flaky ones, or what mark was on them?