Thank you for the post...
I think your little test was quite revealing. I have no idea how the penetration of that tin relates to the tissue of a turkey, but I would guess that it would be similar to penetrating the spinal column of a turkey???
Anyone who has ever broken open a Hevi-shot load knows that the shot is not uniform in size or shape. The #7's will have slightly smaller average size than the #6's, and I would guess that the holes in the tin correlate to larger pellets while the dents correlate to smaller sized pellets (in both tests).
As I remember originally Hevi-13 referred to the density of the pellets (i.e. lead being 11 gms/cc, original Hevi-shot at 12 gms/cc and Hevi13 being 13 gms/cc). I swear I remember marketing touting the increased density at some point, but currently Hevi-13 is the same density as the orginal Hevi-shot at 12 gms/cc... I believe the only difference currently is that that Hevi-13 has a higher payload, but the shot is actually the same... Someone please correct me if I am incorrect, and please post a link...