First, the internal geometry of the .643 SSX tube is unique, in that the ported portion of the tube has a larger internal diameter which doesn't even contact the FliteControl wad. With that said, in my gun w/ the SSX, the Fed. HW 6's and 7's didn't produce "hunting patterns" comparable to what I get w/ an IC .660 and Hevi-13 loads even w/ consideration for the reduced pellet count in the HW loads. I haven't had the opportunity to evaluate the SSX tube w/ the Win. LB shells.