On a reloading group on FB, Dave Brown replied in a discussion about primer safety and trying to kill primers with WD40 and removing the anvil to make dummy cartridges. He appears to be a movie set gun expert and this is informative.

"Don't.
Leave this to the professionals.
The comments here are a very good reason NOT to listen to people who don't do this for a living.
If we need fake primers for close-up shots, we buy the empty cups in bulk from the manufacturer. Once the cup is inserted, you MUST then put a BB inside the case to create a "rattle dummy."
Considering this is three weeks after the 23rd anniversary of the death of Brandon Lee on the set of "The Crow," this is an extra reason NOT to do this yourself.
(Brandon Lee died because they sent the firearms expert home early; bought live rounds for a close-up scene and simply dumped out the powder and shoved the bullet back into the case. During the close-up, the props assistant wasn't paying attention and an actor pulled the trigger. This resulted in a 'primer pop,' where the bullet ended up an inch into the barrel. A week later, they loaded a blank without checking the barrel first. There was no professional on set to check the barrel, and - most tragically - no expert on set to show the actor Michael Massee how to 'cheat' the angle to the side. One foot to the side would have saved Lee's life. Incidentally, blanks have two to three TIMES the amount of gunpowder as actual rounds.)
Plus, we ONLY use rattle dummies when we absolutely need a close-up where we can see the primer. The reason professionals don't use them for routine dummy cartridges is that we MUST take every round out, shake it in front of the 1st AD and EVERY actor in the scene who is holding the gun or having it pointed anywhere near them. We then repeat this for the crew.
If the trigger is pulled on a rattle dummy - and it always will eventually, it is no longer useable for close-ups.
You will notice professionals create most dummy rounds by removing the primer entirely if it does not need to be seen. That way, we can do a final demonstration of safety by pulling the trigger at least once through EVERY chamber. (There is a famous story in the film industry about Robin Williams who once asked me why I ALWAYS pulled the trigger eight times on a six-shot revolver. I told him, "The first six are for you; the seventh one is for me; and the eighth one is for Brandon Lee.")
Don't EVER use fired cases with a fired primer as a dummy! This is extremely dangerous, as there is no way to tell for certain if it is a dummy or a misfire that is going to bang on the next trigger pull.
Or maybe the next trigger pull. Or the one after that ...
PLEASE don't fuck around with this. We have gone 120 years since the dawn of filmmaking with zero fatalities on a film set when firearms are handled by professionals. Every single fatality (Jon-Erik Hexum; Brandon Lee; Halyna Hutchins) was caused by a production wanting to save money by hiring an amateur. Every. Single. One.
The fact that your friend asked you to even attempt this is a signal that that person should NOT be handling guns on film sets!"

This is timely since Baldwin is now being tried civilly for his negligent discharge

There's a bonus section on the Equalizer TV series DVD set from the 1980s (the one with Edward Woodward). In it, Keith Szarabajka recalls working with Robert Mitchum on several episodes. On one occasion, the propman/armourer handed a gun to Mitchum to use, without showing clear first. This didn't fly for Mitchum and he pointed the gun down toward the ground, fired it and a series of blanks went off. He then chastised the propman to do his job better, as only Mitchum could...