The bullet is made up of softer material than the cylinder of the revolver... If the bullet were to hit the front of the chamber from the front, the bullet could easily swage itself into the opening of the cylinder as described, even in a situation like this when the round fired is a larger caliber than the weapon that was hit. I am sure you are not going to pull out an intact .40 round, but a portion of it, and fragments of it were deflected into the suspect or continued past him or off into another direction.
I also know from first hand experience in structured force on force training, that when someone presents a handgun in a threating manner with the intent to shoot, the weapon is pretty much inline with that persons center of mass (which is generally the portion of a target you are trained to shoot at in an encounter), and obscures a fair amount of it depending on the distance. I have been hit many times in the knuckles and hand (hurts like hell) when going through numerous training scenarios, and its not hard for me to picture something like this happening at all.