"Blank Firing Adapter" an ugly orange painted device that is fixed to end of your M-16 restricting the gas flow from the blanks out the barrel so that your weapon will cycle as per live rounds. Without the gas blowback created by a real bullet travelling through the barrel, the weapon will not function. So when firing blanks, you must use these to make the weapon cycle properly. If you do not restrict the gas flow with this you will have to fire one blank at a time and manually eject the casing!.
Make sure your b.f.a. is secured properly over the flash suppressor, that could be why your weapon is not cycling in this training exercise!