over a million civilian stops of crimes per year, using guns? Have you looked into the number of miscreants hit with bullets during such crimes? The number is well under 10,000 per year.
So, if Kleck's number are accurate, not 1 time in 100 do you have to hit the bad guy with a bullet. He leaves at just the sight of the gun (ready in time). The NRA"s Armed Citizen column, every month, for many decades, always states (and provides examples) that many attacks are stopped by just the sight of a gun in the hand of a defender. Many more are stopped by shots fired that don't hit the bad guy, too.