After going through a Carlson .665 and 2 Indian Creek chokes .665 and .675, my NWTF Super X2 24" barrel didn't disappoint yesterday with the new Rob Roberts Gunworks Final Strut .660 choke. 218 Hevi-13 #6 shot in the 10" at 40 yards with a 3.5" 2 1/4oz load and a dirty barrel...also did 125 in 10" with Lead #5 Federal FC 2oz
I think I've found the answer