AR6460 = legislation enforcement semi-car carbine with retractable stock and sixteen inch long barrel and bayonet lug I have never selected a flat top or A1 (devoid of FA and deflector).  I'm thinking a 16" flattop, in addition to a 10.5" with have cope with like yours.  I've a number of Aero slick uppers With all the deflector, just just in cas