A fastener applying apparatus (20) includes an anvil half-section (100) and a cartridge receiving half-section (200) having a distal portion dimensioned to releasably receive a single use loading unit ("SULU") (400) and a proximal portion configured to support a firing assembly (500). The firing assembly includes a stationary housing (502) and a firing lever (516) having one or more lever guide projections (522). The firing lever is slidable from a proximal end of the stationary housing to a distal end of the stationary housing to define a firing stroke. A clamping lever (300) is movable from an undamped position to a clamped position to releasably secure the distal anvil portion in close approximation with the SULU. The clamping lever defines one or more lever guide slots (316). The lever guide projection(s) is positioned to enter the lever guide slot(s) upon initiation of the firing stroke to inhibit movement of the clamping lever to the undamped position during the firing stroke.
