The influence of the duration of the explosive pulse on the size of the resulting crater is investigated. Various factors affecting its size are considered. For this purpose, experiments were carried out at the mines of AO Sevuralboksitruda. It is established that the radius of the explosive funnel is equal to the radius of distribution of a wave of stresses for the duration of an explosive load, defined depending on the point of initiation of a charge, and cannot exceed the size of the radius of a cracking zone at influence on a monolithic rock massif by energy of explosion of an elongated charge. The minimum length of the charge, providing the maximum possible size of the blast funnel radius, depends on the initiation scheme, the detonation rate of the explosive used, physical and mechanical properties of rocks of the blasted massif and is determined by the obtained formulas.