During a thirty year career, from 1972 until 2002, CSM Gammon served in a variety of significant senior non-commissioned officer positions including Command Sergeant Major of the 99^th Support Battalion, 9^th Infantry Division, Division Support Command, Quartermaster NCO Academy, 23^rd Quartermaster Brigade, 45^th Corps Support Group, 25^th Infantry Division, Division Support Command, and the U.S. Army Quartermaster Center and School. 

His expertise in combat logistics made him a highly sought after resource and asset in the teaching of logistics doctrine to enlisted Quartermaster soldiers. Upon retiring in 2002, CSM Gammon began a Department of the Army Civilian career where he currently serves as the Division Chief of the Directorate of Quality Assurance Division, Combined Arms Support Command, where he is responsible for the quality of logistics training. 

His awards include the Legion of Merit, Meritorious Service Medal (3 oak leaf clusters), Army Commendation Medal (3 oak leaf clusters), Parachutists Badge, and Air Assault Badge.