It is not a C-More. I thought maybe C-More might have an updated railway red dot coming up but a quick look on their main website and Google shows this is not the case. Edit: This is a C-More...
The other reason I know its not ATN is because the one in the OP uses hex screws to mount if you look closely.
True. I doubt anyone willing to spend that kind of money on a SBR would throw a $70 reflex sight on it anyway. Maybe some kind of modified C-More?
Would be one hell of a custom job, the entire housing is a different shape all the way up to the circular roof.
Mystery solved. OKO - Czech Repulic made. http://magnumshooterssupply.com/OKO-Red-Dot-Reflex-Sights_c18.htm (US Distributor) Manufacturer: http://www.oktarget.cz/armada_en.html
It looks a lot like this red dot optic made for (or being marketed to) airsoft players to mount on their BB guns: http://www.airsoftgi.com/product_info.php?products_id=6335 (scroll down page to see example of "reflex" red dot sight)
Anyone have any experience with these? It's more or less in the price range I am thinking about for my AR pistol.
Most reviews I've read put them on par with C-More (similar price range), but do suggest getting the extra metal shell for extra protection.