Why do criminals throw the gun at Superman after the bullets bounce off him and why does Superman duck when they throw the same gun at him?

Given that Superman ducks when the gun is thrown at him, this shows his "human" side as his reaction is the same as a normal person. I am sure that the first time someone shot at Superman with a pistol, he probably ducked then too. Criminals figure that just because the bullets did not kill Superman, maybe he will be hurt it they throw the whole gun at him. This shows that crime makes people stupid. ANSWER: The bullets are CGI and the gun is real.