Sergeant Major Jason Bruce Hammock, was born in Miami, Florida and attended recruit training at Marine Corps Recruit Depot, Parris Island, South Carolina.  After graduation from Basic Combat Engineer School, Lance Corporal Hammock received orders to 2d Combat Engineer Battalion, 2d Marine Division, Camp Lejeune, North Carolina.

During his tour with 2d Combat Engineer Battalion, he was deployed with II Marine Expeditionary Force, UNITAS for six months and to Norway for Strong Resolve 98.  Upon his next promotion, Sergeant Hammock served as an instructor at the Engineer Training Area 3, 2d Combat Engineer Battalion.

Following his assignment at 2d Combat Engineer Battalion, Sergeant Hammock received orders to Drill Instructor School, Marine Corps Recruit Depot, Parris Island, South Carolina.  Sergeant Hammock served as a Drill Instructor and Senior Drill Instructor in Company H, 2d Recruit Training Battalion from January 2001 through January 2004.

After a successful tour of duty as a Drill Instructor, Staff Sergeant Hammock received orders to Marine Wing Support Squadron 373, Marine Corps Air Station Miramar, California.  He served there from February 2004 through March 2007 as a Construction Foreman and as the Construction Platoon Staff Noncommissioned Officer in Charge.  Staff Sergeant Hammock deployed to Al-Taqaddum, Iraq with Marine Wing Support Squadron 373 and to Baghdad, Iraq in support of I Marine Expeditionary Force as a member of a transition team. Upon his return from Iraq, Gunnery Sergeant Hammock received orders to Officer Candidate School, Quantico, Virginia.

Gunnery Sergeant Hammock was assigned to Officer Candidate School from April 2007 to September 2010.  During his assignment at Officer Candidate School, Gunnery Sergeant Hammock filled the billet as the Maintenance Chief until April 2010.  After his selection, First Sergeant Hammock was assigned to Company E.  After graduation of his last training cycle, First Sergeant Hammock received orders to Headquarters Battalion, 2d Marine Division, Camp Lejeune, North Carolina.

First Sergeant Hammock reported in September of 2010 as the Company First Sergeant of Truck Company, Headquarters Battalion, 2d Marine Division.  In April of 2011 First Sergeant Hammock transferred to 2d Battalion, 6th Marines, 2d Marine Division where he deployed in support of Operation Enduring Freedom to Nawa, Afghanistan with Company G.  Upon return from deployment, First Sergeant Hammock served as the Headquarters and Service Company First Sergeant.  In December of 2012, First Sergeant Hammock transferred to 2d Marine Regiment and served as the Headquarters Company First Sergeant until his selection to Sergeant Major.

Sergeant Major Hammock reported in August of 2015 to Marine Tactical Air Command Squadron 18 as the Squadron Sergeant Major.  In December of 2016, Sergeant Major Hammock was transferred to Marine Air Control Squadron 4 as the Squadron Sergeant Major.  In August of 2018, Sergeant Major Hammock was transferred to Combat Logistics Regiment 37, 3d Marine Logistics Group as the Regimental Sergeant Major.  In November 2019, Sergeant Major Hammock was transferred to Marine Corps Base Camp Smedley D. Butler to serve as the Director of the Staff Noncommissioned Officer Academy, Okinawa. In June of 2021, Sergeant Major Hammock reported to Marine Corps Logistics Command to serve as the Command Senior Enlisted Leader.  Sergeant Major Hammock transferred to his current post in July of 2023 as the Command Senior Enlisted Leader of Marine Corps Installations Command.

Sergeant Major Hammock has a Bachelor of Science degree in Business Administration. Sergeant Major Hammock's personal decorations include the Legion of Merit, Meritorious Service Medal with two gold stars, Navy and Marine Corps Commendation Medal with combat distinguishing device and three gold stars, the Navy and Marine Corps Achievement Medal with two gold stars, and the Combat Action Ribbon.