I am gathering every thing i need to build my first AR-15. I am going with a rock river arms 20" standered A4 upper with chromed bolt carrier group, chrome molly 1,9 twist barrel to take advantage of the 5.56 being shot from the correct length barrel. For the bottom half i am going with the rock river arms lower with a two stage trigger and mill spec operators 6 postion stock. i will also be getting the quad full length rail for the front. this is my first build and hopfully my last, i have never messed with this platform outside the millitary so any thoughts oppinions or sugestions are very welcome.