RRA Flat-Top Upper
This upper is awesome, save for one well documented scratch, and is priced accordingly.
I bought this upper from Legal Transfers awhile ago, and it fits my RRA lower perfectly -- no play but not tight. On my Bushy lower it fits with just a small bit of play -- usual for the more mil-spec lowers.
When I started fitting my Bushmaster barrel into this upper, a tiny protrusion on the barrel nut scraped a line through the anodizing, leaving the mark pictured below. I stopped inserting the barrel with about 1/4 inch to go, so the scratch is well covered by where a barrel nut goes. That is to say, none of this scratch will show, is well inside the area covered by the barrel nut, and is purely cosmetic.
Otherwise it's beautiful. This RRA upper has wonderful tolerances, more 'right on' than the Bushmaster uppers I've compared it to. It's never been assembled or used beyond just test fitting parts. That's full disclosure.
Edited to add: No, it's not at all purple. It's very black.
$65 by Postal money order. Shipped USPS Priority with tracking.