The only possible reason to include TSS 7s in a turkey load are to make them legal in states that will allow those but not a straight load of 9s (Bless their backward hearts). TSS 7s have the penetration to kill turkeys to 120 yds while sacrificing pattern density, thus decreasing the load's effective range. It's akin to duplexing lead 8s with 2s in a dove shell.