The Movie Timeline - it's like a timeline, but of movies
Full Metal Jacket - timeline
January: During the Communist Tet offensive, Marines include Joker come under sniper fire. (Hue, Vietnam)
January: The film is in two halves, Marine training in the US, Marines in action in Vietnam. We know that the fighting in the latter half takes place in Hue so this places events in late January 1968, the time of the communist Tet offensive. For some reason you also have 1963 listed for this film. The only reason for this could be the assumption that the training sequence takes place in '63. There is no evidence for this in the film that Im aware of. Its more likely that the first half is set in 1967, though this is never said. (City of Hue, South Vietnam)