A surgical instrument for stapling tissue includes a body, a shaft assembly, and an anvil. The shaft assembly includes a stapling head assembly and an actuator. The anvil is configured to be selectively coupled to the actuator. The anvil is configured to cooperate with the stapling head assembly to staple tissue. The anvil comprises a head and a shank extending from the head. The shank includes a proximal end, a distal end, a lumen, and an engagement feature. The engagement feature is in communication with the lumen such that the engagement feature is configured to move relative to the axis in response to the rod being directed into the lumen. The engagement feature is configured to selectively couple the shank to the actuator. The proximal end of the engagement feature is radially fixed relative to the axis.
