I recently picked up a 5rd box of Hevi Shot’s relatively new “Hevi Duty” frangible buckshot in #4 buck. It was $10 for a box of 5rds, (that was a discount/sale price!) as I wanted to take one apart and see what it’s all about.
There were 30 #4 frangible buck pellets which were silver in color, as opposed to the usual sintered copper color, this is their proprietary lead free “EnvironMetal” which is some sort of Tungsten Matrix. The total weight of the buckshot was 365.5gr.
The thing that got my attention was the flax seed hulls used as a crimp-buffer. I have not seen this before, and after researching it, found that Hevi-Shot does this simply to ensure a well-buffered flat surface with no irregularities when crimping the top of the shell. Some of the seed hulls had trickled into the shot, and it might offer some degree of shot buffering as well.
The flax seed hulls registered at 18.8gr