I have become a devotee of the Dewey coated rod. They're coated, very rigid, do an excellent job, and are available in lengths that will take care of the strongest barrel.
Yes, they're on the pricey side. But it's money well spent, because when used properly you almost completely eliminate the possibility of damage to the rifle by cleaning.
Also, you should immediately invest in a bore guide built for the AR series. They're plentiful and when used will keep that rod centered in the bore--which is exactly where you want it.
Hiding in plain sight...