Laser ablative acceleration method is a very useful method to study the hypervelocity impact problem (HVI), i.e., impact of accelerated foil on solid target, crater formation, and other accompanying effects. The essential problem of these investigations is to check the influence of experimental conditions (laser energy, pulse time duration, material and configuration of the target, etc.) on the velocity of the accelerated foil. In this paper, the dependence of accelerated foil velocity on the heavy layers (Ag, Au) covering Al foils was considered. Conversion of the laser energy into x-ray radiation in the heavy material layer can cause an additional acceleration of the foil due to the rise of the ablation pressure. Results obtained show that craters are smaller and more irregular compared to the results of our earlier investigations when foils without heavy cover were used. It means that the acceleration process is now less effective. These results are rather unexpected ones. Some reasons for this situation are pointed out.