A spin stabilized projectile unit includes a sub-caliber projectile having a cylindrical section connected to a conical tail section including an external circumferential holding groove. A propelling cage casing encloses the projectile. A propelling base includes a receptacle holding the projectile and connected with the projectile and the propelling cage casing. The receptacle includes inwardly projecting axial webs presenting an inner diameter of the receptacle in a region of the cylindrical section of the projectile which corresponds to the outer diameter of the cylindrical section. The inner diameter of the receptacle formed by the webs becomes increasingly larger than the respective outer diameter of the conical section beginning in the transition region between the cylindrical and conical sections to form an annular gap extending to a bottom region of the bottom of the receptacle. A segmented holding ring is disposed between the inner diameter of the receptacle and the outer diameter of the conical tail section and lies in the holding groove and against the inner diameter of the receptacle for holding the projectile in the receptacle of the propelling base.