Prop master Lucien Charles, who has worked on shows like "The Blacklist," "FBI: Most Wanted" and "Saturday Night Live," said that "negligence" allowed a live round to get into the gun on the set of Alec Baldwin's film, "Rust"
"That should never have happened. The guns are always checked or need to have checked and that should not have happened," Charles told CNN.
Charles said that there should "never" be a live round on set.
In terms of how movie sets handle having guns on the premises, Charles said "there's a lot of checks and balances."
"The prop master gets the gun from a vendor. If the armorer is involved, they'll get the gun and check it. When it's off set, there's a safety check, bring your crew around with the AD (assistant director), go over the gun with the actors and any crew members interested in seeing the gun. Then it's handled off from the prop master to the actor and that's where it ends right there."