An apparatus for stapling tissue comprises a stapling head assembly, a rotary drive shaft, and a mode selector. The stapling head assembly comprises a closure assembly and a firing assembly. The closure assembly is operable to clamp tissue against an anvil. The firing assembly is operable to drive at least one staple through tissue toward the anvil. The mode selector is operable to select between a tissue clamping mode and a firing mode. The rotary drive shaft is operable to actuate the closure assembly in response to selection of the tissue clamping mode. The rotary drive shaft is operable to actuate the firing assembly in response to selection of the firing mode. The mode selector may translate the rotary drive shaft between a first longitudinal position and a second longitudinal position to select between the tissue clamping mode and the firing mode. The mode selector may comprise a sliding ring.