the axial direction f axial distance between the rear edge 28 of the rotating band 27 and the outer edge of the curvature g distance axial between the rear edge of the rotating band 27 and the upper edge of the boat tail 24 the radial distance between the edge of the convex portion 21 and the inner edge 29 of the boat tail 24 i e the width of region 19 is substantially smaller than the caliber d and essentially corresponds to the transition radii between the curved portion 21 and the inner surface of the boat tail 24 in the following fig3 to 6 this region 19 is omitted i e the curvature directly follows the inner boat tail edge 29 a projectile base 30 will now be described in greater detail in which a curved portion 31 of a base plate 33 has the shape of a spherical cap fig3 a shows the projectile base 30 according to the invention in its rest state the projectile base 30 has a base body 32 with a base plate having a spherical cap 31 for a rear surface and a conical tail section or boat tail 34 the boat tail 34 has a circumferential edge 35 the parachute cavity the rotating band and the rear edge of the rotating band are given the reference numerals 36 37 and 37 39 38 and 38 39 respectively instead of relationship 1 the curvature the convex portion or spherical cap 31 of the base plate 33 can also be described with the aid of the following relationship it must additionally be considered.