I have built all my own AR's besides one that I had custom built for me (vietnam era carbine repro) I have used RRA, Stag, LMT, Model 1 sales, Knights Armament, YHM, Badger Ord., tango down, magpul, and numerous other companys parts and have found thhem all to be of great quality, I would stay away from Hesse or Vulcan but the rest are great. My newest one is made with an ER Shaw 20" ss barrel, flat top upper, Super Sniper scope, and a Stag lower. I custom built the pistol grip and I am about to customize a cheek weld on the buttstock next. I could have bought a Bushy for what I payed to build this but the adventure and satisfaction is what it is all about.