A surgical instrument is adapted for stapling tissue in a highly controlled manner. The surgical instrument includes a frame having a proximal end and a distal end, with a handle positioned at the proximal end and an end effector positioned at the distal end. The end effector includes a supporting structure shaped and dimensioned for selectively receiving a generally C-shaped cartridge module containing a plurality of surgical fasteners. A firing mechanism is associated with the end effector and the cartridge module for selective actuation of the surgical fasteners. The cartridge module includes a cartridge housing and an anvil, the cartridge housing and the anvil being relatively movable between a first spaced apart position and a second position in close approximation with one another.
