I own a 14.5" 1/7 currently and sold a 16" 1/9 recently. Both in 5.56 with chrome lined barrels.
The 1/9 was very accurate IMO for a chrome lined barrel (<1.25" 5 shot groups).
The jury is still out on my current upper (awaiting range time.)
They both run/ran dependably
I've read on the 6.8...