Surgical stapling apparatus

A surgical stapling apparatus (stapler) is provided and is configured to couple to a reload. The reload includes a first jaw member releasably supporting a cartridge that includes a slide deflector that is movable from a first position to a second position. One or more lockout steps are provided on one of the first and second jaw members of the reload. A drive member includes a working end urged to move toward the lockout step. In the first position, the slide deflector is positioned to prevent engagement of the working end of the drive member with the lockout step, and in the second position the slide deflector is positioned to allow engagement of the working end with the lockout step to prevent further advancement of the working end. Distal translation of the working end causes the slide deflector to move from the first position to the second position.