As we had way to many blank rounds in our bunker my NCOIC said it was OK to fire the 60's as a demonstration. I took about 12 of the 20MM cans of blanks and rigged two M60's with "our" blank adapters.
We would take off the flash supressor and pound a empty piece of brass with a reamed out primer flash hole into the muzzle of our spare barrels we had designated as "blank training barrels only" and then replaced the flash supressor. Worked better than the clamp on blank adapters and looked the part also.
I let all those wannabe heros and kids (age 8-80) try and shoot the M60 like Rambo did in the movie...............It was a hoot !
Stay Safe !
Watch closely...you'll see weapons "fire" even when the slides are locked back. They save the blanks for close-ups.
Not surprising, really. It stops the habit of blank-only weapons have of breaking down, causing expensive retakes. Considering the notoriously bad safety habits of actors, it's probably safer, too. Some have been killed playing grabass with blank guns. One idiot a few years back actually died when, jokingly, he put a blank loaded .44 Magnum to his head and fired.