There ya go
Because he wanted to make sure the terrorist was not merely dead but sincerely dead
Because...the first shot didn’t stop the perp, the second shot didn’t stop the perp, the third shot didn’t stop the perp, the fourth shot didn’t stop the perp...
But the fifth shot brought down the perp, which was good because now the good guy was out of bullets.
A nineteen year old male fully jazzed on adrenalin is not easy to kill. Consider something in .44 caliber or greater for next time.