PURPOSE: To prevent shooting of a bullet out of a practice field by opening a plurality of cutout grooves opened longitudinally and radially outwardly on stable wings at the rear of the bullet.
CONSTITUTION: Cutout grooves 8a are opened on stable wings 8 attached to the rear of a columnar bullet 10 longitudinally and radially outwardly. After a training tank bullet 7 is charged in a barrel and shot, a bullet cylinder 6 is immediately separated from the bullet 10 by air pressure acting it, and the bullet 10, the wings 8 are flown toward a target. In this case, air resistance is not varied at bullet flying speed Mach 4 - 5 by the pneumatic characteristic of the grooves 8a, but abruptly increased at Mach 4 or lower. Thus, it can prevent the bullet from arriving out of a practice field.