I can't tell you much about your components, my experience is limited to a Olympic barrel and EA lower.
But I will say this: When you go for the benched group testing try some quality ammo first. When I put together a 16" flatop this summer the first groups off the bench were sub-minute. This was using some handloaded bolt gun ammo I had worked up with IMR4985 and good Sierra 60 grain HP bullets. I was freakin' amazed at my new gun. Then I opened up the White box Q1313ABR549 (whatever it is) 55 grain FMJ from WallyWorld and started having +3" groups.
If I had started with that cheap ammo I sure would have been a less than happy camper with the new gun and the groups I shot.
Oh yeah, I did float the barrel from the get go (Hogue CAR forend) and later install a JP adjustable trigger and speedhammer. IMHO money well spent in both cases.