Gunnery Sergeant Justin Grunes enlisted in the United States Marines Corps in July 2002 and attended recruit training at Marine Corps Recruit Depot Parris Island. 

His assignments during his first enlistment were as a clarinetist with III Marine Expeditionary Force Band, Okinawa, Japan and with the 1st Marine Division Band in Camp Pendleton. In 2006, he deployed with the division band to Fallujah, Iraq for Operation Iraqi Freedom 5–7, operating there as a security platoon attached to 5th Marine Regiment. He left the active ranks of the Corps in April 2007 to pursue a music degree at the University of Delaware.

Shortly after beginning studies at UD, GySgt Grunes transferred service branch and reenlisted as a reservist with the 287th Army Band, Delaware National Guard. He graduated cum laude in 2011 and returned to the active duty Corps the following year.

In September 2012, GySgt Grunes reported to Parris Island Marine Band to resume his service in the Corps. This assignment was followed by advanced musical training at the Naval School of Music’s Unit Leader Course starting in the Fall of 2014. After graduating the following May, GySgt Grunes reported to Marine Band San Diego where he carried out a two-year tour as an instrumentalist.

In August 2017, GySgt Grunes was recalled to the School of Music to serve as a clarinet instructor. He also fulfilled responsibilities as Woodwind Branch Head, Physical Training Team Leader, Information Systems Coordinator, and Equal Opportunity Representative. 

GySgt Grunes reported to 2d Marine Aircraft Wing Band in October 2020. Prior to his current assignment as the band’s Enlisted Conductor, he had served as the unit’s Platoon Sergeant and Small Ensemble Leader.

GySgt Grunes’s personal awards include the Navy and Marine Corps Achievement Medal (2nd award) and the Army Achievement Medal.