This is complete horse manure. I’ve shot blank rounds in five or six different calibers. They always had either a crimped case mouth, or a wad or plug of wax or paper composition that did not protrude beyond the case mouth. They never were charged with anything remotely similar in appearance to a jacketed or non-jacketed bullet. You could teach a six year old to distinguish between them. A qualified armorer would be able to tell them apart from 10 feet away.
Nowhere in this article is the term “blank” or “blanks” used.
There is a difference between blanks and dummy rounds.
on movie sets there are different kinds of dummy rounds.
Some are blanks like what you’re talking about, with crimped ends. Some are rounds with bullet, case, and inert primer made for close-up shots like when the revolver is pointed right at the camera where the audience is supposed to see the bullets in the chambers or where the character is loading the gun.
Multiple sources have suggested that these are supposed to be filled with BBs that rattle when shaken but I can’t tell if that’s an industry standard or not.