A surgical stapling apparatus, comprising:a housing；an elongated member extending from the housing；a tool assembly supported on a distal end of the elongated member, the tool assembly including a first jaw member and a second jaw member；a cartridge assembly releasably supported on the first jaw member, the cartridge assembly including an actuation sled including at least one mechanical interface；an anvil operably supported on the second jaw member, the anvil including at least one spring and defining a stop； anda drive member having a working end including at least one mechanical interface；wherein the spring is configured to urge the working end of the drive member to position the working end of the drive member in alignment with the stop on the anvil to prevent the working end of the drive member being advanced distally, andwherein the at least one mechanical interface on the actuation sled is positioned to engage the at least one mechanical interface on the working end of the drive member to retain the working end of the drive member out of engagement with the stop to allow advancement of the drive member through the tool assembly.
