What is Gun Down?
1.
(v.) To shoot someone with a firearm. This term came into coinage in the British tabloids in the 1960s, and world war I before that (where it was mainly military speak for a machine gunner, see b))
a) The paramilitrist said he was going to gun down a politician.
b) You don't want to go through that gap, there's a gun down in there.
See