Here is what would have really happened after the Hartman murder-suicide
If you've seen Full Metal Jacket, then you probably recall the scene where Private Leonard "Gomer Pyle" Lawrence snaps, killing his tormentor, Gunnery Sergeant Hartman, and then himself. The film then segues to 1968, where "Joker" and "Cowboy" are both sergeants — as if the incident had no effect on their careers.
It would not have gone down that way. To put it mildly, the killing of Gunny Hartman is likely merciful end when compared to the hell he would catch in the wake of such an incident. A murder-suicide like that would, in all likelihood, rock the entire Marine Corps.
At the time Full Metal Jacket was taking place, drill instructors like this one would have been supervised by officers.
(U.S. Marine Corps)
Immediately after the tragic event, both the Navy Criminal Investigative Service and the United States Marine Corps Criminal Investigation Division would move in to investigate what happened. Joker, Cowboy, and everyone in the recruit platoon would be thoroughly interrogated. That "blanket party" would come back to haunt them — they'd get non-judicial punishment as a best-case scenario. Worst-case scenario could involve courts-martial, like the one in A Few Good Men, and a potential for dishonorable discharges.
NCIS agents - the real-life version of Leroy Jethro Gibbs - would be investigating the murder-suicide,
(Photo by Bill Wheatley)
But it doesn't stop there. The Naval Inspector General's office would come in and start asking a lot of questions — not just of the Marines in the platoon, but of the entire chain of command at Parris Island. If you think the recruits had it bad, well, some of the officers would likely see their careers end.
Brig. Gen. Austin E. Renforth's counterpart in Full Metal Jacket would likely see his career hit a dead end in the wake of the Hartman-Lawrence murder-suicide.
(U.S. Marine Corps)
In the wake the 1956 Ribbon Creek incident, in which a DI got six recruits killed during night march through a swamp, officers were required to more closely supervise recruit training. The DI was court-martialed and charged with negligent homicide.
In the wake of an incident like the one portrayed in Full Metal Jacket, the lucky ones would get relieved and receive letters of admonition or reprimand and would close out their careers long enough to get retirement. Unlucky ones would face the "up or out" realities of promotion. And the really unlucky ones would get court-martialed.
In short, the Hartman-Lawrence incident would cause a ton of havoc. The case would have spawned media headlines, and Pyle's fellow recruits would probably be infamous among their fellow Marines – if they hadn't already been booted out.