I have ordered a 20" Lothar Walther fluted stainless barrel (including barrel extension & headspaced bolt), 1:10 twist, .936 gas block and threaded 5/8"-24 for the last 3/4" of the barrel at the muzzle. I'm going to be mating a Bennie Cooley compensator to it. I'm also going to be buying: Magpul PRS, Tubbs Flat Wound recoil spring, Enidine AR-Restor recoil buffer, Fulton Armory Chromed BCG, ATC SR Gold Trigger, and Magpul MIAD grip. I'm up for recommendations on the mag release, bolt catch, and various other small miscellaneous lower parts, and safety lever etc.