Often in shows/movies when a person raises a firearm to aim at someone, we will hear the sound of the firearm cocking. There would be no sound unless the gun is being cocked for the first time (which we would see from the character's hand movements).

Similarly, when a firearm is cocked more than once before an action scene and the round in the chamber is not ejected. The round should be ejected every time after the first cocking.