Sergeant Major Metzger enlisted in the Marine Corps in April 1991. After completing recruit training aboard Marine Corps Recruit Depot, San Diego, CA, PFC Metzger attended Marine Combat Training aboard Camp Pendleton, CA. He was transferred to his Military Occupational Specialty (MOS) School aboard Meridian, MS as an Aviation Supply Clerk. After completing his initial MOS training, PFC Metzger was chosen to attend follow-on training to earn the additional MOS of 6694, Aviation Information Systems Division Operator. PFC Metzger was promoted to the rank of Lance Corporal during his follow-on training. Upon completion of his MOS training, LCpl Metzger was transferred to Marine Aviation Logistics Squadron (MALS) 14, MCAS Cherry Point, North Carolina. He was promoted to the Rank of Corporal during his tour with MALS-14.

In 1995 Cpl Metzger was transferred to MALS-12, Iwakuni, Japan. While with MALS-12, Cpl Metzger deployed on a Unit Deployment Program to Darwin, Australia. Cpl Metzger was promoted to the rank of Sergeant in 1995 and was transferred to the Presidential Helicopter One (HMX-1), Quantico, VA.

Sgt Metzger completed the Aerial Observer syllabus for the CH-53E Super Stallion Helicopter and flew with the HMX-1 squadron (Green-Side) during his tour at HMX-1. After his tour with HMX-1, Sgt Metzger was transferred to the Drill Instructor School, Marine Recruit Depot, Parris Island, SC.

Upon completion of Drill Instructor School, Sgt Metzger was assigned to Golf Company, 2d Battalion, Recruit Training Regiment. Sgt Metzger was promoted to the rank of Staff Sergeant in 1999 and filled the billets of Drill Instructor, Senior Drill Instructor, and Series Chief. SSgt Metzger was meritoriously promoted to the rank of Gunnery Sergeant in 2002 and subsequently transferred to MALS-31, Marine Corps Air Station, Beaufort, SC in July 2002.

While with MALS-31, GySgt Metzger held the billets of Squadron Gunnery Sergeant and AISD Chief. He was promoted to the rank of First Sergeant in 2005 and transferred to Direct Support Motor Transport Company B(-), Inspector Instructor Staff, Lubbock, TX, 6th MTBN, 4th MLG as the Inspector Instructor First Sergeant.

Upon completion of Inspector Instructor duty, First Sergeant Metzger was transferred to India Company, 3d Battalion, 7th Marines, 1st Marine Division, Twentynine Palms, CA and deployed to OIF 8-02.

First Sergeant Metzger was promoted to the rank of Sergeant Major in May 2010 and was transferred to Combat Logistics Battalion 7, Combat Logistics Regiment 1, 1st Marine Logistics Group as the Battalion Sergeant Major and deployed to OEF.

Returning from OEF, SgtMaj Metzger was transferred to Marine Light Attack Helicopter Squadron 467, Marine Aircraft Group 29, Cherry Point, NC as the Squadron Sergeant Major until 2014.

In February 2014, SgtMaj Metzger was assigned to Marine Helicopter Squadron One, Quantico, VA.

SgtMaj Metzger's personal decorations include the Meritorious Service Medal with two gold stars, Navy Marine Corps Commendation Medal with two gold stars, and the Navy Marine Corps Achievement Medal with one gold star and the Presidential Service Badge.