So its actually very simple and pretty realistic in the game,

DISCLAIMER: This might not work for every gun especially for calibers like 45. ACP and below, make sure you use JHP for the best outcome. Sometimes you just have to shoot more often at this area but when you use the right gun it will mostly be a 3-4 hit until the suspect is down. Best gun for that is the MK-V with AP rounds, wich is a one hit.

Short answer: Blow their ♥♥♥♥♥ away. Higher caliber = better (dont try it with shotguns because they'll probably die)

Long answer: Shoot the pelvic bowl. The pelvic bowl is the area where your hips and everyones most valuable part is the ♥♥♥♥, cat or whatever you have there. The reason is simple the pelvis acts like the "core frame" of the body, it holds your spine, supports your upper body and connects both legs. So if you shatter the pelvic bowl with a bullet it firstly hella hurts and secondly you cant walk for ♥♥♥♥ because your entire lower body basically loses its foundation.

Little yapping part: I love how the developers have added this very realistic detail, even tho you'd expect this from a hardcore realistic SWAT game its still pretty cool

Thx for viewing and i hope this helps you on reaching a high score