I honestly know nothing about them except for what i have read on the internet, and the ~300 rounds ive put through my buddys. He has a RRA something. Problem is, i live right near a city, so most places you cant shoot .223. So what im thinking is getts a 9mm and later buy a .223 upper and remove the block from the magwell and such if i want to shoot .223. but for the options of places i have to shoot, 9mm is where i have to be. so, i guess my question is do i buy or do i build? I'm leaning towards building due to slow income of funds, and saving is difficult . I am not sure what all goes into an AR, or even where the best places to shop around are. Any info, links, opinions would help so i can go from there. thanks!!