An experimental study of fibers breakage in a starve-fed single screw extrusion is presented. A long glass fiber-reinforced polypropylene (LGF-PP) was investigated at various operating conditions. The “screw pulling-out” technique was used to study fibers breakage along the screw and its dependence on the melting mechanism. The solid conveying, melting position, the extent of starvation, and the fully filled regions were observed. Polymer samples were stripped off from the screw, which was removed from the machine, to investigate fibers distribution by means of a metrological computed tomography (CT) system. Contiguous solid melting (CSM) mechanism was observed for flood fed extrusion of PP filled with 30% LGF. Dispersive solid melting (DSM) replaced CSM for starve-fed extrusion of PP filled with 40% LGF and blended with neat PP in order to achieve a fiber fraction of 30%. Fibers breakage was significantly reduced with DSM, as the pellets are not compacted into a dense solid bed and forced to melt against the barrel.