I know some military moves, most martial arts require 'extremely precise' attacks, IMO, why bother? a solid hit to the offending parties nose with an open fist, (if your in extreme danger ONLY) and there....either dead or knocked out cold for a fair while, REPEAT use only in periods of extreme danger to your or your loved ones.
another one is a solid blow to the base of the neck (at the back).
if you jsut want to knock someone down and leave them gasping for air for 2 minutes...enough time to run away, hit them just below the indented bone in the chest.
i learnt these from my brother and sister both of whom are currently in the army, and they are deadset serious moves, i am not in any way encouraging that someone use these moves unless your life or others are in danger.