Known commonly to United States Military as the Blank Fire Adapter. This barrel cover is screwed down to prevent blank cartridge from becoming dangerous.
A term adorned by under paid and over worked soliders meaning Butt F#@k Adapter. Used to express frustration of deadly units limited by an ugly orange box at the end of the rifle
GI Joe: Hey Rambo, are you stoked these ugly orange boxes will be defilling our instruments of death? Get ready for 3 hours of team tactics with our BFAs!
Rambo: OHN (o hell no) Joe! This lousy contraption is more like a butt f*#1 adapter!