I would think there would be a strict protocol about emptying any forearm and having it double checked by a second individual before it is brought anywhere near a set where blanks are used.
As I’ve read, the double check is normal protocol....which may have been compromised with the replacement non-union peeps, but even here, the AD announced “cold gun”—indicating OK to proceed—and that gun had previously been prepared by someone else.
One of the two—or both—failed protocols.
Oh, there is, but people get cavalier. It is like the one important work order in a million that needs to be dug up, and it can't be found in the file where it belongs - on a BIG scale.