im afraid that although everyone has shots that hurt them more than others, smacking somone in the nerves in the nerves, or recieving a blow to an organ will have a VERY bad effect on somone.
most people have never taken a proper liver shot, most of the time the force isnt enough to feel the shot within the organ.
put it like this, you can be knocked out by a liver shot, the extreme pain and shock of the blow causes your body to pass out!