This is correct.

Imagine the opportunities for fuck-ups that would happen if every ignorant, bonehead actor who was given a gun on set said, "Hold everything while I disassemble this MP-5 to check the barrel for obstructions, and unload every mag to verify that there are only blank rounds in it!"

Actors should definitely receive basic firearms safety training if they're going to be using guns on set, and they should have the understanding that even blanks can kill.

But it is definitely not their job to be gunsmiths.

Also, imagine a movie where all the real firearm safety rules were enforced.

Director: Okay, in this scene, you point your gun at the bad guy and say, "Freeze, asshole!"

Actor: But I must never point a gun at anything I do not intend to destroy! How about I don't pull my gun, and I say "Freeze, asshole, or I will pull my gun out and point it at you!"

Hey, better to be safe, right?