Even without a model number on the cap ring, a 146 is most likely genuine; counterfeits of the 146 are hardly known, presumably because the piston mechanism is too elaborate for counterfeiters. There are simply two variants: with and without printed model number. A somewhat stiff piston often comes from dried ink and becomes smoother again with regular use; a smooth-running piston as on some other brands is, however, structurally not to be expected on the 146.