When the film Full Metal Jacket was being cast, real-life former Marines Sergeant, Ronald Lee Ermey was hired as a consultant. Apparently, in Ermey's opinion, none of those up for the role of the sergeant in the film was right for the part, but director Stanley Kubrick was still not convinced saying that he was "just not mean enough" based on having seen him in 'The Boys In Company C.'
R. Lee sent him a clip with him shouting insults while dodging tennis balls which evidently was enough to impress Kubrick who cast him in the unforgettable role of the Sergeant Hartman.
R. Lee Ermey was born in 1944 and served over a decade in the US Marine Corps including 14 months in Vietnam and Okinawa, Japan. It was in Okinawa that he became a staff sergeant. His first film role was as a helicopter pilot in Francis Ford Coppola's classic Apocalypse Now and shortly after that the role of a drill instructor in The Boys In Company C.
According to Kubrick, about half of the memorable lines from Sgt Hartman in Full Metal Jacket were improvised on the spot by Ermey.
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(Warning, the above video features extremely graphic language)
<blockquote>Kubrick told Rolling Stone that 50% of Ermey’s dialogue in the 1987 film was his own. “In the course of hiring the marine recruits, we interviewed hundreds of guys. We lined them all up and did an improvisation of the first meeting with the drill instructor. They didn’t know what he was going to say, and we could see how they reacted. Lee came up with, I don’t know, 150 pages of insults,” Kubrick said.</blockquote>
Ermey was also a board member for the National Rifle Association and a spokesman for Glock.