where did the rank gunnery sergeant come from
Gunnery sergeant The rank of gunnery sergeant in the Marine Corps was established by the Navy personnel act of March 3, 1899 (30 Stat. L., 1009) reflecting the duties of Marines in ship's detachments. The original insignia was three chevrons point up with three straight "ties" with an insignia of a bursting bomb over a crossed rifle and naval gun. From 1904 to 1929 the insignia went to three stripes only over a bursting bomb on top of crossed rifles. In 1929, like the rank of first sergeant, two "rockers" were added beneath the stripes with the same insignia in the middle. In 1937 the middle insignia was dropped. The rank was replaced by technical sergeant in 1946 until restored in 1959, when the crossed rifles insignia were added to Marine chevrons.[6]
Military rank "The [U.S.] commissioned officer corps is divided into 10 pay grades (O-1 through O-10). Officers in pay grades O-1 through O-3 are considered company grade officers. In the Army, Marine Corps, and Air Force, these pay grades correspond to the ranks of second lieutenant (O-1), first lieutenant (O-2), and captain (O-3), and in the Navy, ensign, lieutenant junior grade, and lieutenant. Officers in the next three pay grades (O-4 through O-6) are considered field grade officers. In the Army, Marine Corps, and Air Force, these pay grades correspond to the ranks of major (O-4), lieutenant colonel (O-5), and colonel (O-6), and in the Navy, lieutenant commander, commander, and captain. The highest four pay grades are reserved for general officers in the Army, Marine Corps, and Air Force, and flag officers in the Navy. The ranks associated with each pay grade are as follows: in the Army, Marine Corps, and Air Force, brigadier general (O-7), major general (O-8), lieutenant general (O-9), and general (O-10); in the Navy, rear admiral-lower half, rear admiral-upper half, vice admiral, and admiral."[10][11]