Calvin Alan Byrd (born December 17, 1979), professionally known by his stage name 40 Cal., is an American rapper.

He was a member of Harlem-based hip-hop group The Diplomats.

Byrd made his first appearance on the self-titled theme song, "40 Cal" for the Dipset album Diplomatic Immunity 2.

He took a part on MTV2's Fight Klub MC battles.

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