I've evaluated numerous choke load combinations and have settled on the following:
Indian Creek .675 31/2" EM MagBlends
Indian Creek .665 31/2" EM 6's & 7's
I get good even 20" patterns w/ both chokes w/ a denser 10" center core. The .665 pattern w/ MagBlends is a little more open than the .675. All my shells are "old" stock from the first year of production of the MagBlends and 7's and the previous years production of the "gold hull" 6's. I have not shot any of the current production shells.
I never found a choke which gave me a satisfactory "hunting pattern" w/ the Federal HW shells, but have been told that the Trulock designed for the Flitecontrol wad is giving the best patterns.