This was some years ago and I do not remember the lesson verbatim, but I believe I recall the gist of it: Getting shot sucks, although it will likely suck much less if you are wearing body armor and the round hits you in it. We were instructed that incoming fire has the right of way, and cover should be sought when possible. Getting shot with a .357 Magnum round sucks more than getting shot with a .45 ACP round, which sucks more than getting shot with a .40 cal round, which sucks more than getting shot with a 9mm round (the test results he showed us were from JHP defensive rounds, not FMJ). If you know you're getting into a fight with people wearing body armor, try to bring a rifle and friends with rifles. The body armor defeating drill we were taught was designed to use a volume of center-mass shots so that the "back face signature" (in other words, damage done by a bullet that does not penetrate) or outright defeat of the body armor (by hitting it in the same area repeatedly) to slow or even stop the assailant, before considering a shot to the ocular vault.