When it comes to pop-culture allure and romanticized brutality, Stanley Kubrick’s “Full Metal Jacket” is arguably the most influential of all Vietnam War movies. R. Lee Ermey’s iconic portrayal of the sadistic Gunnery Sgt. Hartman has served as a de facto recruiting mechanism for the Marines since the film’s release in 1987. But many fans are unaware of some of the juiciest bits of behind-the-scenes drama and literary awesomeness from the film and its source material. Consider this list the enthralling special-features bonus DVD you never saw.