A surgical instrument including a power assist device, and its method of use for deploying surgical fasteners, is disclosed. The surgical instrument may include a handle, an elongated shaft extending from the handle, and a surgical fastener deployment system including a driveshaft. The driveshaft is actuatable between at least a first proximal position and a second distal position. A striker is movable relative to the driveshaft and an impact surface is associated with the driveshaft. The impact surface is constructed and arranged to be struck by the striker member to displace the driveshaft to the second distal position and deploy the surgical fastener.