The Hevi stuff is loaded into the shell on top of the steel. The flax seeds are supposed to act like a buffer and tighten up the pattern, or at least the Hevi portion of the pattern. When I tested this stuff this past season, I could not tell exactly which pellets struck where in the pattern. Logic would dictate that since patterns bloom from the center out (the leading pellets are always the first to be pushed aside), the Hevi stuff would generally migrate to the outside edges of the pattern. Based on the size of the shot in the loads that I measured, I couldn't tell. I did talk to another fellow who is a well respected member of this board, and he told me that in his tests, that was definitely the case, the Hevi stuff migrated to the fringes. If that is true, and I have no reason to doubt him, then the flax seed does very little in the way of acting as a buffer.
Based on the tests I made, the size of the Hevi stuff in these loads does not conform to SAAMI standards and is not HeviShot. It is definitely heavier than steel at 10.7gm/cc, but lighter than lead and HeviShot. And while there is an increase in the number of pellets to a ballistically comparable steel load (1 1/4oz steel #2 = 156 pellets vs 1 1/4oz #2 HeviMetal = 171 pellets), the increase was nowhere near the advertized 23%. Furthermore, these pellets seem (according to my tests) to help populate the outer annular ring, which is actually a good thing. But there are actually far too few additional pellets (15) to make much difference.
I had no way of testing for penetration with any level of comparative accuracy, so I have to assume that "ballistically equal" means that the pellets are at least equal to #2 steel. Based on actual field use, they did not perform as well as standard. spherical steel shot of good quality (purely subjective here). In other words, in my opinion, they didn't kill ducks any deader. Although I did not shoot these loads past 40 yards, pattern tests indicated that the patterns degraded faster than did the Dryloks and Remington NitroSteel loads it was compared against.
I feel slightly sorry for a man who has never patterned his gun, who has no idea how far his chosen load will retain killing penetration. But I'm extremely sorry for the ducks he shoots at beyond the killing range of his gun and load - Bob Brister