t=200/v

The drop is 0.5 * g * (200/v) 2m.

Assuming the bullet speed is 600m/s, the calculated drop is 0.54m m.

The problem of bullet rotation mentioned upstairs, the gun bore is designed to rotate the thread bore to make the shot bullet rotate, in fact, it is to ensure that the bullet always faces forward when moving, thus reducing the resistance. This problem has been said not to consider air resistance, so it is not in the calculation.