[en] The experimental study is carried out of some specific methodical aspects of the use of the gamma-gamma method for the express-sampling of lead-zinc ores in containers taking into consideration the screening effect of walls. The principal attention is paid to the study of the effect of the γ-radiation backscattering from the container walls on the intensity and spectral composition of the secondary radiation. The studies performed allow to evaluate the contribution of the container walls to the intensity of the dispersed gamma-radiation, to determine the optimum distance between the beam axis and the detector