An experimental and theoretical study of the behavior of a List/Buss Kokneter is presented. The experimental study which uses polypropylene considers (I) the interaction of the Kokneter with a crosshead screw extruder, and (ii) distribution of polymer in the modular screw. A modeling study considers the dynamics of flow including the influence of screw oscillation. Calculations are made for various individual Buss elements. A model is developed for the total system including the crosshead screw extruder. It is shown that an oscillating length of fill in the crosshead screw extruder can account for the throughput oscillation stabilization characteristics of the composite machine. Predictions of pressure profiles and positions of starvation in a starved flow machine are made.