Fin deployment system for a projectile, the fin deployment system defining a longitudinal axis and comprising: an actuator plate, pivotable from a first pivot position to a second pivot position about the longitudinal axis; a first mechanical stop arrangement, configured for initially locking the actuator plate at the first pivot position, and for selectively unlocking the actuator plate from the first pivot position responsive to an actuating force, to thereby allow the actuator plate to pivot to the second pivot position; an actuation assembly for selectively applying the actuating force to the first mechanical stop arrangement, to thereby unlock the actuator plate from the first pivot position; a plurality of fin assemblies, each fin assembly including a fin pivotable from a stowed position to a deployed position about a respective fin hinge defining a respective deployment axis, each fin assembly forming a kinematic pair with the actuator plate such that said pivoting of the actuator plate between the first pivot position and the second pivot position, and said pivoting of each fin from the respective said stowed position to the respective said deployed position, are concurrent; and a second mechanical stop arrangement for locking the fin assemblies in the respective deployed positions responsive to the actuator plate pivoting from the first pivot position to the second pivot position, characterized in that the fin deployment system further comprises an outer casing, and an inner support bracket internally mounted to outer casing, the fin assemblies being pivotably mounted to the outer casing about the respective deployment axes, and the actuation assembly being mounted to the inner support bracket. an actuator plate, pivotable from a first pivot position to a second pivot position about the longitudinal axis; a first mechanical stop arrangement, configured for initially locking the actuator plate at the first pivot position, and for selectively unlocking the actuator plate from the first pivot position responsive to an actuating force, to thereby allow the actuator plate to pivot to the second pivot position; an actuation assembly for selectively applying the actuating force to the first mechanical stop arrangement, to thereby unlock the actuator plate from the first pivot position; a plurality of fin assemblies, each fin assembly including a fin pivotable from a stowed position to a deployed position about a respective fin hinge defining a respective deployment axis, each fin assembly forming a kinematic pair with the actuator plate such that said pivoting of the actuator plate between the first pivot position and the second pivot position, and said pivoting of each fin from the respective said stowed position to the respective said deployed position, are concurrent; and a second mechanical stop arrangement for locking the fin assemblies in the respective deployed positions responsive to the actuator plate pivoting from the first pivot position to the second pivot position, characterized in that the fin deployment system further comprises an outer casing, and an inner support bracket internally mounted to outer casing, the fin assemblies being pivotably mounted to the outer casing about the respective deployment axes, and the actuation assembly being mounted to the inner support bracket.