Just to give everyone another data point on accuracy - I bought the same upper as OP from Brownells. Dropped in an extra bolt I had lying around (I think it was a blemished Toolcraft), Dead Air muzzle device and spare charging handle and took it out to the range today. Mostly just sighted in my Vortex scope at 50 yards. However, just for fun did shoot one 5 round group at 100 to get an idea of its accuracy and shot some steel at 200 yards.
Using my 1x6 Vortex scope, 77 gr. IMI ammo and resting gun on front sandbag (no rear bag) my 5 shot group at 100 yards was about 1.5"-1.7". I have no doubt that with a better shooter, better ammo, more magnification and a rear bag that group would shrink to probably something below 1 MOA.. Then took some shots at 6" steel at 200 yards. Even with cheap XM193 I was getting about 90% hits. Given my intended use of this gun that's acceptable accuracy. Add the barrel life you're going to get out of a DD barrel and I think this is a winner.