A surgical instrument that includes a surgical end effector that is coupled to a shaft assembly by an articulation joint. A flexible firing beam extends through the articulation joint to interface with a firing member in the surgical end effector to apply a firing motion thereto. In at least one form, the surgical instrument further includes a movable firing beam support assembly that is configured to movably contact the firing beam on each lateral side thereof as the firing beam flexes about the articulation joint.
