Cosmoline, you are missing one point - cost. Computer generated effects are expensive and time consuming. It's still easier and cheaper (in a long run) just to take a real gun and convert it to blank fire. And a real gun doing real firing is just... real looking! With no effects added. It really depends on the movie, but most of the times weapons are real or at least blank firing replicas.
Rubber or plastic molds of weapons are used for stunts, or when the weapon is not too close to the camera to see the details of it.
Probs master does not handle weapons - movie armourers do. And they are responsible for the safety and proper handling. The armourers are loading the weapons, handling them to the actors /stunt men/, clearing them after the scene and storing them until the next scene. Trust me on this - I have several friends that are dedicated movie armourers. In the big Hollywood movie recently shot in Bulgaria almost all of the guns you are going to see are real and shooting blanks all day long.
Boris
