Gunnery Sergeant is pay grade E7, and the equivalent Army rank is Sergeant First Class.

SSG stands for Staff Sergeant. That is higher than a Sergeant. The next rank will be Gunnery Sergeant.

Master Sergeant is a rank in the Marines. Master Gunnery Sergeant, Major and Major General are additional Marine ranks.

Gunnery Sergeant and Lance Corporal are names of ranks used by the US Marines. The Question was about the US Army.

Gunny means Gunnery Sergeant. It is a military rank of the Marines.