I have never shot the first load of steel shot. My opinion os steel shot v body armor is you're looking at a non-starter. It takes different properties to punch thru armor as compared to flesh.
On the other hand, unprotected heads, legs, arms and crotches remain vulnerable when wearing body armor so far as I know.
To touch again on the relative penetration of shot versus bullets in game animals, I've seen a similar result with use of CB shorts as compared to HVHP shorts an SV LR bullets. Expansion reduces penetration irrespective of impact energy, mass or energy. CB shorts will penetrate far deeper than HVHP ammo, or even SV LR. The CBs retain whatever SD they start with while the higher velocity bullet expand greatly...and stop. I think the analogy works with buck and conicals for the same reason.
