A surgical instrument, comprising: an elongate shaft assembly comprising an input shaft; a surgical end effector, comprising: a staple cartridge portion; an anvil supported for selective movement relative to said staple cartridge portion; a firing shaft operably supported by said staple cartridge portion, said firing shaft operably interfacing with said input shaft such that said firing shaft is actuated upon application of an actuation motion to said input shaft; and a firing member movably supported in said staple cartridge portion for selective axial movement between start and end positions in response to said actuation of said firing shaft; and a closure member operably interfacing with said input shaft and configured to axially move from a beginning position to an ending position, and wherein a clamped position is located intermediate said beginning and ending positions, characterised in that the anvil comprises a mounting portion comprising at least one pin slot, wherein said closure member comprises at least one pivot pin configured to be received in a corresponding pin slot in the mounting portion of said anvil, wherein each said pin slot comprises: a proximal slot portion corresponding to said beginning position of said closure member; and a distal slot portion joining said proximal slot portion at an apex point corresponding to said clamped position such that said distal slot portion is not axially aligned with said proximal slot portion, so that said clamped position corresponds to a position wherein said closure member retains said anvil in a fully closed position, and further actuation of said input shaft after said closure member has attained said clamped position causes said firing member to move from said start to said end position and said closure member to move from said clamped position to said ending position while retaining said anvil in said fully closed position. an elongate shaft assembly comprising an input shaft; a surgical end effector, comprising: a staple cartridge portion; an anvil supported for selective movement relative to said staple cartridge portion; a firing shaft operably supported by said staple cartridge portion, said firing shaft operably interfacing with said input shaft such that said firing shaft is actuated upon application of an actuation motion to said input shaft; and a firing member movably supported in said staple cartridge portion for selective axial movement between start and end positions in response to said actuation of said firing shaft; and a staple cartridge portion; an anvil supported for selective movement relative to said staple cartridge portion; a firing shaft operably supported by said staple cartridge portion, said firing shaft operably interfacing with said input shaft such that said firing shaft is actuated upon application of an actuation motion to said input shaft; and a firing member movably supported in said staple cartridge portion for selective axial movement between start and end positions in response to said actuation of said firing shaft; and a closure member operably interfacing with said input shaft and configured to axially move from a beginning position to an ending position, and wherein a clamped position is located intermediate said beginning and ending positions, characterised in that the anvil comprises a mounting portion comprising at least one pin slot, wherein said closure member comprises at least one pivot pin configured to be received in a corresponding pin slot in the mounting portion of said anvil, wherein each said pin slot comprises: a proximal slot portion corresponding to said beginning position of said closure member; and a distal slot portion joining said proximal slot portion at an apex point corresponding to said clamped position such that said distal slot portion is not axially aligned with said proximal slot portion, a proximal slot portion corresponding to said beginning position of said closure member; and a distal slot portion joining said proximal slot portion at an apex point corresponding to said clamped position such that said distal slot portion is not axially aligned with said proximal slot portion, so that said clamped position corresponds to a position wherein said closure member retains said anvil in a fully closed position, and further actuation of said input shaft after said closure member has attained said clamped position causes said firing member to move from said start to said end position and said closure member to move from said clamped position to said ending position while retaining said anvil in said fully closed position.