Some info :
Years of service 19611972 medically retired in 1972 for several injuries incurred during his tours.
On May 17, 2002 he received a promotion to Gunnery Sergeant (E-7) from the Commandant of the Marine Corps (later Supreme Allied Commander Europe (SACEUR)) United States Marine Corps General James L. Jones, becoming the first retired military member in the history of the United States Marine Corps to be promoted.
Correction: On May 17, 2002 he received an honorary promotion to Gunnery Sergeant (E-7) from the Commandant of the Marine Corps
Ermey is a retired Staff Sergeant masquerading as a Gunnery Sergeant.
Thanks CM.Impressive.