A surgical stapling device 10 including a handle assembly 12, a body portion 14 extending distally from the handle assembly, a head portion 16 including an anvil retainer 38 and a shell assembly 31, the anvil retainer being movable in relation to the shell assembly between unapproximated and approximated positions, a tube 160,165 surrounding a portion of the anvil retainer, wherein the anvil retainer 38 includes a distal annular protrusion 177b for releasably engaging an anvil assembly 30 and wherein the anvil assembly includes a center rod 154.
