BFA = A blank-firing adapter or blank-firing attachment (BFA), sometimes called a blank adapter or blank attachment, is a device used in conjunction with blank ammunition. Blank firing adapters are required for allowing blanks to cycle most automatic firearms. It can also be a safety feature designed so if a live round is mistakenly fired, most of the energy is spent smashing through the BFA reducing both the range and damage inflicted. A BFA may also divert the hot gases from a blank discharge out to the sides, reducing the risk of injury to the target of an aimed shot.[1]
Ahhh....the joys of cleaning all that carbon off after a day or two of blatting away with a BFA fitted.... Much cleaner when it's FMJ's going down the spout