Citations:bucky

noun: gun (slang)
In an interview with Ashlene Nand, M.I.A. was asked "what the hell does “Bucky Done Gun” mean?". Her response was:

I don’t know!! (Laughs) I really don’t know. At the time, the concept that I was thinking of was how far we are going to go with gangster culture in rap music. That’s really what I was thinking about. I was thinking about 50 Cent. It started off as Public Enemy and ended with 50 Cent. What was that journey (for rap music) and how did that happen? In London, Bucky is a slang word for gun. It’s a real British, grime word. So I was thinking, what is the aftermath of gangster rap? Were they going to get into therapy?

Source

 * MIA - Real Refugee (dead link, archive)