726X is the officer billet designator code for Ordnance Technician (Submarine) in the U.S. Navy.
Ordnance Technicians are technical specialists in ballistic missile weapons systems, including:
Missiles
Missile launchers
Missile fire control
Warhead subsystems
The Navy uses four-digit numbers to identify primary naval specialties. To become a chief warrant officer in the Navy, it typically takes around 14-16 years of service.
This includes:
Completing basic training
Attending officer candidate school
Gaining experience in various positions
The Warrant Officer Program is open to all enlisted Navy people with the rank of chief petty officer or above and have completed at least 12 years of naval service.