I've got a 26" "polished" barrel BPS through which I've shot and evaluated almost all of the HTL commercially loaded shells starting w/ the "old" green Remingtons. I have not evaluated the Environmetal Hevi-13 loads produced in the last three years, since I stocked up on 6's, 7's and Mag-Blends based upon my patterning results the first year that the 7's were produced. Of the 8 choke tubes which I evaluated in my BPS, the Indian Creek .665 produced the densest 10" core w/ an even 20" dispersal. I got marginally better patterns w/ the Indian Creek .675 w/ the Hevi-13 4's, 5's and Mag-Blends, but the pattern opened up w/ the 6's and 7's. I usually carry a Hevi-13, 7 in the chamber w/ 6's in the tube as back-up.