Photoemission from atomically uniform layers of Ag on a Fe(100) substrate is employed for the determination of the bulk electronic band structure of Ag. The high degree of control of the layer thickness allows the interferometric measurement of the electron momentum normal to the sample surface. This leads to an unprecedented precision in the electronic band structure determined from the experiment. The high quality of the layers also allows the discussion of the line shape of the quantum well peaks for the first time and gives access to the intrinsic and extrinsic broadening parameters of the line shape.