A surgical instrument, comprising: an elongate shaft assembly defining a shaft axis; a surgical end effector operably interfacing with said elongate shaft assembly for selective rotation relative to said elongate shaft assembly about said shaft axis, said surgical end effector comprising a firing member configured for selective axial movement therein in response to an application of at least one rotary control motion thereto; an end effector rotary locking system interfacing with said surgical end effector and being configured to lock said surgical end effector in rotary orientations about said shaft axis upon application of an axial locking motion to said end effector rotary locking system and to unlock said surgical end effector for selective rotation about said shaft axis upon application of an axial unlocking motion to said end effector rotary locking system; and a rotary drive system configured to apply said at least one rotary control motion to said firing member, said rotary drive system configured to apply at least one rotary positioning motion to said surgical end effector when said end effector rotary locking system is in an unlocked configuration to position said surgical end effector in a selected one of said rotary orientations about said shaft axis, wherein said surgical end effector is operably coupled to said elongate shaft assembly by a mounting fixture configured to permit said surgical end effector to selectively rotate about said shaft axis upon application of said at least one rotary positioning motion thereto and wherein said end effector rotary locking system comprises a rotation locking disc coupled to said surgical end effector for rotational travel therewith upon said application of said at least one rotary positioning motion to said surgical end effector, said rotation locking disc further configured to frictionally engage said mounting fixture to prevent rotation of said surgical end effector about said shaft axis upon application of said axial locking motion to said end effector rotary locking system, and characterised in that said rotation locking disc comprises a plurality of locking detents radially arranged thereon wherein each of said locking detents corresponds to one of said rotary orientations and wherein said end effector rotary locking system further comprises a lock member supported for selective movement into locking engagement with a corresponding one of said locking detents upon said application of said axial locking motion thereto. an elongate shaft assembly defining a shaft axis; a surgical end effector operably interfacing with said elongate shaft assembly for selective rotation relative to said elongate shaft assembly about said shaft axis, said surgical end effector comprising a firing member configured for selective axial movement therein in response to an application of at least one rotary control motion thereto; an end effector rotary locking system interfacing with said surgical end effector and being configured to lock said surgical end effector in rotary orientations about said shaft axis upon application of an axial locking motion to said end effector rotary locking system and to unlock said surgical end effector for selective rotation about said shaft axis upon application of an axial unlocking motion to said end effector rotary locking system; and a rotary drive system configured to apply said at least one rotary control motion to said firing member, said rotary drive system configured to apply at least one rotary positioning motion to said surgical end effector when said end effector rotary locking system is in an unlocked configuration to position said surgical end effector in a selected one of said rotary orientations about said shaft axis, wherein said surgical end effector is operably coupled to said elongate shaft assembly by a mounting fixture configured to permit said surgical end effector to selectively rotate about said shaft axis upon application of said at least one rotary positioning motion thereto and wherein said end effector rotary locking system comprises a rotation locking disc coupled to said surgical end effector for rotational travel therewith upon said application of said at least one rotary positioning motion to said surgical end effector, said rotation locking disc further configured to frictionally engage said mounting fixture to prevent rotation of said surgical end effector about said shaft axis upon application of said axial locking motion to said end effector rotary locking system, and characterised in that said rotation locking disc comprises a plurality of locking detents radially arranged thereon wherein each of said locking detents corresponds to one of said rotary orientations and wherein said end effector rotary locking system further comprises a lock member supported for selective movement into locking engagement with a corresponding one of said locking detents upon said application of said axial locking motion thereto.