Good tactical body armor will stop a rifle round. My CHL carry sidearm wouldn’t even sting him if he was wearing that type of ballistic protection.
Were he wearing a standard DOJ IIIA rated concealable vest...... Yes it would hurt like the dickens an derail his plan A for sure.
My opinion.... Stay Safe !
With all the other gear, he may have had the up-armored vest. So, aim for the mask.
Take care