Hey guys. Just traded for a Armalite ar-10. Grew up shooting bench rest rifles so I am not an expert on this thing yet. I purchased it to be able to do some range work and some hunting. 1. It is an A2 model and as I look around this site it seems like the majority are flattops. Is it a big disadvantage to run this setup? 2. Where do you guys recommend looking for an upper receiver? Seems like it is hard to find them for the armalites. Thanks for your time guys.