Explosive ammunition drive charge - has differential dia. ducts with some sections smaller than value required for pressure ignition but greater than that after gas ignition

The solid fuel propulsion charge for ammunition is provided with internal ducts of different diameters. The diameters of part of these ducts are smaller than the critical value required to ensure ignition in these ducts under the action of the ignition pressure but greater than the critical value after the gas pressure has increased above the ignition pressure. The charge may be of a type which is increasingly deformable at increasing temperature so that the smaller-diameter ducts become narrower through compression under the action of the gas pressure in the larger-diameter ducts and at the outer surface of the charge.