I don’t own any of the MR series and probably never will. If you can’t take the upper and (without modification) install it on a full auto lower, I don’t want it. That’s your reason for all those that “just don’t get” why it makes a difference. Making an 11” 416 upper is not a challenge with a factory in the US. Go ahead, yeah the problem is the German government, blah, blah, blah.