A single pellet strikes the pelvis, the subject is going to drop, strikes the spine, going to drop, strikes (and penetrates) the skull, going to drop.... Any of those will drop him like a sack of bricks but may or may not be fatal, and may or may not stop them from fighting. I have seen people with a clean 9mm hole through the bottom of their left ventrical in their heart go on fighting for 2 minutes like nothing happened, only to bleed out and die a minute later. Shots that contact the spinal cord, or the brain stem are the only true "will always stop the attack" kind of shots, but the target is fractions of an inch wide. Shots to the subframe (the pelvis) will normally drop the person, but they may not stop fighting or shooting. A single pellet from a #4 shot could sever the spine and cancle the party, but the chances are slim, the target is small and the risk of them continuing to fight is too great to hope for that.