In a magnetic field assisted internal finishing process using an abrasive slurry circulation system, magnetic particles are driven by magnetic force in a helical path along the inner surface of the tube, propelling the abrasive slurry and thereby removing material. The dynamic behavior of the magnetic particles must control, therefore, the roughness and lay of the surface and material removal. It was found that the geometrical and magnetic properties of the particles remarkably affect the configuration of the magnetic particles and their dynamic motion at the finishing area. This modifies the abrasive contacting mechanism against the surface and alters the finished surface characteristics, either uniform micro-scratches in the direction of the abrasive motion or multi-directional marks of aggressive abrasive contact. These characteristics must directly affect the surface quality of the tubes used for safety and sanitary technology applications. This paper characterizes the behavior of the magnetic particles in view of their geometrical and magnetic properties and the effects of these properties on the finishing characteristics. The finishing experiments also demonstrate that controlling the geometrical and magnetic properties of the particles is of use in extending the feasibility of the process.