Provided is an apparatus for dispensing a composition that includes a barrel having an inlet and outlet, an extrusion screw, and a drive mechanism operatively coupled to the extrusion screw. The extrusion screw includes a shaft having a shank end for connection to the drive mechanism and a distal end opposite the shank end. A first helical flight extends around a first section of the shaft, and a second helical flight extends around a second section of the shaft. The second section is located distal to the first section and the first helical flight has a nominal outer radius less than that of the second helical flight, and optionally the first helical flight has a pitch shorter than that of the first helical flight.