rock river parts ID

[StinkyCheeze]

How does one ID the maker of the upper receiver on these rra upper receivers? Lower has prominent emprint. How about the other components? Furniture, add on rails, Bolt & carrier, etc. What do you look for in an original? .....The main thing is how to tell if a 2nd hand gun for sale is really a RRA original or just a built upon lower receiver...Thanks :)

[StinkyCheeze]

How would one ID the uppers on --ANY-- brand AR 15 for that matter? Being a novice it seems difficult to assure pedigree an these weapons. Many folks seem to like building their own from "God only knows what" :) LOL . These are nice, modular machines and I look forward to learning how to ID parts acurately. THANKS.