You guys crack me up! 
Lowers have no effect on accuracy! Plain and simple I promise you that if you take a upper and shoot the same ammo with the same shooter and use 30 different lowers and use just one trigger the groups will stay the same!!!!
But then again I guess we can start using a sloppy lower as a reason why are groups opened up.....
"Well it would have been a sub .5 if my lower wasn't so sloppy on my upper!" 
