A shell assembly for use with a handle assembly, the shell assembly comprising: a shell body having a proximal end and a distal end a cartridge supporting a circular array of staples secured to the distal end of the shell body a main pusher supported within the shell body and movable between an initial position, an advanced position, and a retracted position a knife pusher selectively secured to the main pusher and a compressible member disposed between the main pusher and the knife pusher, the compressible member movable from a first position wherein the compressible member is disengaged from the knife pusher to move the main pusher to the advanced position independent of the knife pusher, and a second position wherein the compressible member engages the knife pusher to facilitate advancement of the main pusher and the knife pusher to the advanced position, wherein movement of the main pusher to the retracted position moves the compressible member from the first position to the second position.
