A milling tool (201o-203o) for use in a wellbore, comprising: a tubular housing; a plurality of circumferentially aligned openings formed in the housing; one or more pistons (210,211a,b); a plurality of arms, each arm: located within a corresponding one of the plurality of openings, moveable relative to the housing between a retracted position and an extended position, and having an inner body portion and an outer blade portion, the body portion having an actuation profile formed in one side which faces a mating guide extending from a surface of the housing, wherein the respective actuation profile and the guide are operable to move each arm radially outward as the arm is pushed longitudinally upward by the piston (210,211a,b) wherein: the milling tool (201o-203o) is movable between a deployment configuration in which said arms define the retracted position and a casing cutting configuration in which said arms define the extended position, and when the milling tool (201o-203o) is in the casing cutting configuration, the arms are in the extended position and a lateral blade sweep dimension is more than fifty percent greater than an outer diameter of the housing. a tubular housing; a plurality of circumferentially aligned openings formed in the housing; one or more pistons (210,211a,b); a plurality of arms, each arm: located within a corresponding one of the plurality of openings, moveable relative to the housing between a retracted position and an extended position, and having an inner body portion and an outer blade portion, the body portion having an actuation profile formed in one side which faces a mating guide extending from a surface of the housing, wherein the respective actuation profile and the guide are operable to move each arm radially outward as the arm is pushed longitudinally upward by the piston (210,211a,b) located within a corresponding one of the plurality of openings, moveable relative to the housing between a retracted position and an extended position, and having an inner body portion and an outer blade portion, the body portion having an actuation profile formed in one side which faces a mating guide extending from a surface of the housing, wherein the respective actuation profile and the guide are operable to move each arm radially outward as the arm is pushed longitudinally upward by the piston (210,211a,b) wherein: the milling tool (201o-203o) is movable between a deployment configuration in which said arms define the retracted position and a casing cutting configuration in which said arms define the extended position, and when the milling tool (201o-203o) is in the casing cutting configuration, the arms are in the extended position and a lateral blade sweep dimension is more than fifty percent greater than an outer diameter of the housing. the milling tool (201o-203o) is movable between a deployment configuration in which said arms define the retracted position and a casing cutting configuration in which said arms define the extended position, and when the milling tool (201o-203o) is in the casing cutting configuration, the arms are in the extended position and a lateral blade sweep dimension is more than fifty percent greater than an outer diameter of the housing.