An experimental and numerical investigation of the electromagnetic (EM) scattering by reformed radar targets (objects with an aperture) is proposed. The applied Gaussian Beam (GB) methods are: GB Summation (GBS) and GB Launching (GBL). Therefore, the theoretical formulations of GBS and GBL are established. Then, the GBS and GBL techniques are examined with the Physical Optic and Physical Theory of Diffraction (PO+PTD) model, the Method of Moment (MoM), and the measurements. The variations of RCS are simulated as a function of various parameters: incident angle, azimuth scattering angle, frequency band, and the target type. The simulation results show that the GBS and GBL provide accurate modeling of the scattering by a disc with and without notch. In addition, the simulation and the experimental investigations of the scattering by a cylinder with an aperture show the influence of the aperture of the scattered field and demonstrate the validity of the used GBS and GBL techniques.