A surgical cutting and stapling end effector. Various embodiments comprise a channel that is configured to operably support a removable staple cartridge. A rotary end effector drive shaft is supported within the channel and is configured to move a firing assembly longitudinally within the end effector to cause the sled to eject surgical staples from the staple cartridge. The firing assembly is prevented from moving distally through the channel unless a surgical staple cartridge that has a sled in a starting position has been seated within the channel.
