A surgical stapler comprising a tool assembly, wherein the tool assembly comprises: a channel assembly for mechanically mounting a staple cartridge therein; a staple cartridge assembly releasably mechanically mounted in the channel assembly, the staple cartridge assembly carrying a plurality of staples; an anvil assembly dimensioned to deform said plurality of staples ejected from said staple cartridge assembly thereagainst during stapling; a sled movable through said staple cartridge assembly from a first position to a second position, wherein said sled includes at least one angled surface (161a,161b) which upon movement thereof forces said plurality of staples from said staple cartridge assembly through tissue and against said anvil assembly to deform and close the staples about tissue disposed between said anvil assembly and said staple cartridge assembly; a dynamic clamping member movable with said sled through said channel assembly and said anvil assembly, said dynamic clamping member having a first mechanical interface which slidingly engages said anvil assembly during stapling and a second mechanical interface which slidingly engages said channel assembly during stapling, said first and second mechanical interfaces of said dynamic clamping member being in substantial vertical registration relative to one another to oppose the expansive forces associated with clamping and stapling tissue and to maintain a substantially uniform gap between tissue contacting surfaces of said anvil assembly and said staple cartridge assembly during stapling, characterized in that the staple cartridge assembly including the sled and the dynamic clamping member is adapted to be selectively releasably mounted to and removed from the channel assembly to facilitate replacement of the staple cartridge assembly including the sled and the dynamic clamping member. a channel assembly for mechanically mounting a staple cartridge therein; a staple cartridge assembly releasably mechanically mounted in the channel assembly, the staple cartridge assembly carrying a plurality of staples; an anvil assembly dimensioned to deform said plurality of staples ejected from said staple cartridge assembly thereagainst during stapling; a sled movable through said staple cartridge assembly from a first position to a second position, wherein said sled includes at least one angled surface (161a,161b) which upon movement thereof forces said plurality of staples from said staple cartridge assembly through tissue and against said anvil assembly to deform and close the staples about tissue disposed between said anvil assembly and said staple cartridge assembly; a dynamic clamping member movable with said sled through said channel assembly and said anvil assembly, said dynamic clamping member having a first mechanical interface which slidingly engages said anvil assembly during stapling and a second mechanical interface which slidingly engages said channel assembly during stapling, said first and second mechanical interfaces of said dynamic clamping member being in substantial vertical registration relative to one another to oppose the expansive forces associated with clamping and stapling tissue and to maintain a substantially uniform gap between tissue contacting surfaces of said anvil assembly and said staple cartridge assembly during stapling, characterized in that the staple cartridge assembly including the sled and the dynamic clamping member is adapted to be selectively releasably mounted to and removed from the channel assembly to facilitate replacement of the staple cartridge assembly including the sled and the dynamic clamping member.