By too much scope, do you mean too much magnification? For what its worth, I have an 8-32x Target Dot scope on my .22lr tackdriver. I don't think there's such a thing as too much scope, if you like a small field of view with more magnification, thats good.

What are you plans for the two rifles? Is the 16" AR10 more of a fun gun, or do you plan to stretch its legs to long distances. Same goes with the HBAR AR15, at what distances do you normally shoot it?