Just a shame that that's not how they work in reality... The fireblast generates next to no explosive force, meaning automatic and semi-auto shotguns won't cycle and the expended round will just stay in the barrel until it gets manually racked.
Would be quite the spectacle otherwise, though.
Oh yeah... that's a good point. I was thinking about that with blanks earlier today, I wonder if they carry enough force. I guess they must, unless their "semi-auto" use in movies is purely CG. I know they're dangerous at close range, but the visible "blast" and Hollywood-level sound explains that, even if they lack the force to "power" the mechanism.
...
*MANUALLY ejects the shell in your general direction*
I actually have some experience with this! Basically: It depends. Some blanks are loaded/designed in such a way that they do in fact cycle the weapon they're in. The (red) practice blanks we got in the army did not do this (although there were blue blanks that
were powerful enough to do so, we weren't special enough to get those), so we had to manually rack our automatic rifles after each and every shot. Which is especially fun since the HK416 is designed to be ambidextrous, meaning that the "bolt" is in the middle of the gun and you have to bend your elbow all funky-like and do this weird cripple gangsign in order to manually load a new blank into the chamber. Good stuff!
Also there are adapters you can install onto the gun, and in some cases gas pressure settings that can be configured on the gun itself that will let it cycle with blanks.