Which rank is denoted by the insignia of 3 chevrons above crossed rifles above 3 rockers?

The rank represented by the insignia of 3 chevrons above crossed rifles above 3 rockers is indeed Master Sergeant (MSgt). This insignia reflects one of the key elements of the U.S. Marine Corps enlisted rank structure.

The three chevrons indicate the sergeant portion of the rank, which signifies a leadership position. The crossed rifles below the chevrons denote the military occupational specialty associated with infantry units, emphasizing that this rank typically holds a significant amount of experience and responsibility in a combat-related role. The three rockers at the bottom further solidify the specific rank of Master Sergeant, distinguishing it from other non-commissioned officer ranks.

Overall, this insignia is critical in identifying the rank and role of the individual within the Marine Corps, with the combination of chevrons and rockers designed to communicate both leadership experience and specialized military proficiency.