I have used the red wedges before. They serve a purpose. There can be enough tolerance stacking between uppers and lowers of different manufacturers that a little movement exists. I've had it between uppers and lowers of known good brands even. The best solution I've found is to use lowers...
This modularity is one of the major caveats to the ar platform. Don't get me wrong, I love ar's. It's one of my favorite platforms. But they can be chambered in so many different cartridges with little or no visible distinction without removing handguards. It really is a recipe for disaster...
No need for a flame suit! It looks correct to my untrained eye, but with no photos of markings :dunno:. How's it shoot?
I would expect to see a forge mark on the right side of the upper. Any marks on the bolt?
Eta: I see the c on the front sight.