Except Three Kings isn’t about Vietnam.
Robin Moore’s book, The Green Berets, (best regarded as a novel) was published in 1965 and there’s enough common material between the two to recognise it as the inspiration for the film.
FMJ was mostly filmed in England; the Hue sequences were done at the disused Becton gas works in east London and the Parris Island sequences were filmed at the old air force base at Bassingbourne, by then the Queen’s Division depot. Soldiers passing through training at the time were offered per diem and a haircut to act as extras. The weapons were supplied by Bob Hills of Hills Small Arms; he appears briefly in the turret of a tank.
Ahh. OK. At first the statement looked like bullcrap to me. But then I recalled jump school. Though not “Green Beret” training, it is definitely a prerequisite. So it counts.
I think that back in the 60s all the training was done exclusively at Camp MacKall (Hell on freaking Earth!!!*) near Ft. Bragg.
The medical portion for the SF Medics might have been in Texas at that time, though.
Now, some phases are at Bragg (I call them the “happy phases”), and others are at MacKall.
** Imagine Hell frozen over – You’d have Camp MacKall in the winter!!!
To continue this, I’d like to mention that FMJ was based on the book The Short Timers by Gustav Hasford. It’s an excellent book and much darker than the film. The book’s title was later changed to FMJ to go along with the movie.