A clip applier loading unit, comprising: a shaft, comprising: a distal end; a proximal end; and a frame comprising a frame connector configured to be releasably attached to a frame of an actuator; a replaceable clip magazine configured to be releasably received in a magazine aperture of the shaft, the magazine comprising a plurality of clips; an end effector extending from said distal end of said shaft, wherein said end effector comprises: a first jaw; a movable second jaw; and a receiver defined between said first jaw and said second jaw, wherein said receiver is configured to receive a said clip, and wherein said second jaw is movable toward said first jaw to deform a said clip positioned in said receiver; and a firing drive, comprising: a distal portion configured to advance a said clip into said receiver in a firing stroke; and a proximal portion comprising a drive connector configured to be releasably attached to a driver of the actuator, wherein said shaft further comprises a bearing, and wherein said firing drive further comprises: a rotatable drive member rotatably supported by said bearing, wherein said rotatable drive member comprises a thread; and a firing nut threadably engaged with said thread of said drive member, wherein said firing nut is configured such that the rotation of said drive member advances said firing nut toward said distal end of said shaft to advance a said clip into said receiver, wherein the clip applier loading unit further comprises a crimping drive configured to move said second jaw toward said first jaw to deform the clip in said receiver in a crimping stroke, wherein said crimping drive is configured to be actuated in sequence with said firing drive by said firing nut selectively disengaging an actuator of said firing drive prior to engaging said crimping drive as said firing nut is advanced toward said distal end of said shaft such that a lag exists between the end of the firing stroke of the firing drive and the beginning of the crimping stroke of the crimping drive. a shaft, comprising: a distal end; a proximal end; and a frame comprising a frame connector configured to be releasably attached to a frame of an actuator; a distal end; a proximal end; and a frame comprising a frame connector configured to be releasably attached to a frame of an actuator; a replaceable clip magazine configured to be releasably received in a magazine aperture of the shaft, the magazine comprising a plurality of clips; an end effector extending from said distal end of said shaft, wherein said end effector comprises: a first jaw; a movable second jaw; and a receiver defined between said first jaw and said second jaw, wherein said receiver is configured to receive a said clip, and wherein said second jaw is movable toward said first jaw to deform a said clip positioned in said receiver; and a first jaw; a movable second jaw; and a receiver defined between said first jaw and said second jaw, wherein said receiver is configured to receive a said clip, and wherein said second jaw is movable toward said first jaw to deform a said clip positioned in said receiver; and a firing drive, comprising: a distal portion configured to advance a said clip into said receiver in a firing stroke; and a proximal portion comprising a drive connector configured to be releasably attached to a driver of the actuator, a distal portion configured to advance a said clip into said receiver in a firing stroke; and a proximal portion comprising a drive connector configured to be releasably attached to a driver of the actuator, wherein said shaft further comprises a bearing, and wherein said firing drive further comprises: a rotatable drive member rotatably supported by said bearing, wherein said rotatable drive member comprises a thread; and a firing nut threadably engaged with said thread of said drive member, wherein said firing nut is configured such that the rotation of said drive member advances said firing nut toward said distal end of said shaft to advance a said clip into said receiver, wherein the clip applier loading unit further comprises a crimping drive configured to move said second jaw toward said first jaw to deform the clip in said receiver in a crimping stroke, wherein said crimping drive is configured to be actuated in sequence with said firing drive by said firing nut selectively disengaging an actuator of said firing drive prior to engaging said crimping drive as said firing nut is advanced toward said distal end of said shaft such that a lag exists between the end of the firing stroke of the firing drive and the beginning of the crimping stroke of the crimping drive. a rotatable drive member rotatably supported by said bearing, wherein said rotatable drive member comprises a thread; and a firing nut threadably engaged with said thread of said drive member, wherein said firing nut is configured such that the rotation of said drive member advances said firing nut toward said distal end of said shaft to advance a said clip into said receiver, wherein the clip applier loading unit further comprises a crimping drive configured to move said second jaw toward said first jaw to deform the clip in said receiver in a crimping stroke, wherein said crimping drive is configured to be actuated in sequence with said firing drive by said firing nut selectively disengaging an actuator of said firing drive prior to engaging said crimping drive as said firing nut is advanced toward said distal end of said shaft such that a lag exists between the end of the firing stroke of the firing drive and the beginning of the crimping stroke of the crimping drive.