Building a AR-15

[ryan.u]

Well folks I going to be getting quite alot of money soon so I fugure I will build a AR-15. But the thing is I know nothing about black rifles but I allredy got the lower reciver picked out now all I need to do is find out what is a good upper reciver. I have a $900 price range for this gun so I am looking into a RRA (Rock River Arms) upper for it

[cowboy bowhunter]

I would go with as much colt as you can get.