We found that the reduced pinning forces of ex situ MgB2 /Fe monofilamentary tapes do not scale with temperature if the external magnetic field is applied parallel to the tape surface. A model is proposed to explain the behavior of the volume pinning forces in parallel and perpendicular orientations of the magnetic field, accounting for the observed texturing gradient between the center of the filament and the MgB2 /Fe interface. The degree of texturing of the sample, as determined by x-ray diffraction, is confirmed by modeling the pinning force in parallel field as the superposition of two components, the first one due to a highly textured region on the external part of the filament and the latter due to a low texturing region in the core.