I know that a 10mm won't penetrate level 3a Kevlar but which round would hurt the most? 220gr hardcast because it is the heaviest? Or 155 TMJ because it has the most muzzle energy and won't deform as easily on the vest surface. Or something else? There have been at least 3 shootings where the BG had armor. Tyler Texas, the CO theater, and Newtown. I have started carrying my rounds staggered in the mag, half 155gr XTP and half 155gr TMJ so if the need ever arises I would have some rounds that might punch deep into a vest and at least buy some time (carrying Underwood ammo in a G29.) Wanna kill these ads? We can help!