The paper presents an analytical approach for determining the effects of different properties of inert material of bulging armor sandwich on its efficiency against a shaped charge jet. The crater and shock wave parameters have been investigated. A theoretical relation for calculating the energy of the shock wave, produced by the jet impact, in the inert material has been derived on the basis of continuity of pressure and particle velocity at the interface of jet and inert material. This relation reveals that the higher the velocity of the jet the greater is the amount of energy in the shock wave. The energy of the shock wave also increases with increase of density and decrease of strength of the inert material. The shock energy has been found to further depend on the constants of equation of state of the inert material, (us=a+b u).