I wonder if it doesn't just come down to a matter of money. Is it cheaper for a movie production to simply rent actual functional firearms than it is for them to rent or otherwise obtain non-functional replicas???
Even if it is, I can't help but wonder about the cost savings balancing the needed cost for safety when real firearms are used on the set.
With movies having budgets running to millions of dollars these days, where does what can only be a small amount of saving really matter, when the possible alternative can be human death?
They've been using reasonably realistic looking rubber prop guns when actors have to do stunts for a long time. Those guns look ok at a distance and are generally not shown close up, and go a long way to helping prevent injury when an actor or stuntman has to jump, fall or do something active while holding a gun.
(though sometimes goofs do get through, there's one in Dirty Harry where you can clearly see the barrel of Harry's "S&W" flex when he jumps onto a ladder...) Anyway rubber prop guns have been in use for generations.
Likewise metal & wood/plastic "replica" guns which look identical to actual firearms but cannot chamber or fire actual ammunition have also been around for as long. I've even owned some.
And then, there are actual firearms that have been modified to only take special blank ammo, and cannot fire live ammo, which have also been around for a long, long time.
And the final group are actual, functional firearms, being used to only fire blank ammo, which have been in use about as long as we've been making movies. The industry has developed an elaborate series of procedures and protocols to protect everyone on the set when actual functional guns are in use, and they do a good job, but, of course they have to be FOLLOWED, not ignored or they don't work.
Obviously. this was not done on the set of "Rust" or we wouldn't have had the accidental death and injury. Many are saying the rules weren't followed and corners were cut to "save money", but I have to wonder, wouldn't actual non firing props have done the same job for the camera and been cheaper??
(and I mean cheaper if they had not had the accident at all?)
I'm not calling for a law or guild rule absolutely prohibiting actual firearms in films, but with todays tech, shouldn't it be an industry "best practice" recommendation?