A surgical stapler includes a first elongate member having a distal portion that supports an anvil surface, and a second elongate member having a distal portion configured to receive a staple cartridge. The stapler further includes a pin rotatably coupled with the first elongate member, and a clamp member movably coupled with the second elongate member. The clamp member is operable to releasably capture the pin to thereby clamp the first elongate member against the second elongate member. The pin is configured to rotate relative to the first elongate member in response to being captured by the clamp member.