In almost every action-comedy movie there is a person who happens to drop a gun and then it goes off. This however just does not happen every time a gun gets dropped. For a gun to be fired it requires the firing pin to be activated and to do so you either need to pull the trigger or get the hammer to release and come into contact with the firing pin. The chances of this happening are slim to none. In fact, a lot of gun instructors will tell you that it is safer to just drop the gun if it falls out of your hand rather than try and catch it. This is because well trying to catch the gun as it falls there is a good chance that you will grab the trigger in the process and discharge the weapon. Even though in all of the movies it looks super dangerous to drop a gun it really isn't as bad as what they make it out to be. However if you are dropping a gun I don't think it should have been in your hands in the first place.