This is probably a stupid question, but is a usable shotgun without a barrel an NFA item?
Maybe they just chopped the barrel off (at the receiver) for the video? I’ve taken apart my Remington 870 before, and the barrel locks back into the receiver. If it wasn’t just chopped, I don’t know how the shell wouldn’t fly out of place without being locked properly into something when it was fired. I could be wrong though.
Hat tip: Bryan