What Harry was doing with his other hand while pointing his gun at the downed bad guy:

DIRTY HARRY: "BUT BEING THAT THIS IS A .44 MAGNUM, THE MOST POWERFUL HANDGUN IN THE WORLD, AND WOULD BLOW YOUR HEAD CLEAN OFF, YOU'VE GOT TO ASK YOURSELF ONE QUESTION: 'DO I FEEL LUCKY?' WELL DO YA, PUNK?"; LUCKY