Guys,
We have a bit of confusion in terminology here. This just shows why it's important that we always cut the other fellow some slack and don't necessarily jump to the conclusion that "I'm right... the other fellow is a moron."
Coriolis Effect is not the Same as Spin Drift...
Spin Drift -- Spinning Earth Effect vs. Spinning bullet effects
Coriolis Effect--
At very long range the rotation of the earth,which effectively moves the target) has an effect on bullet trajectory/impact. This IS caused by a spinning planet, but it is not what is normally called "Spin drift."
Wiki: "For small arms, this rotation is generally insignificant, but for ballistic projectiles with long flight times, such as extreme long-range rifle projectiles, artillery and intercontinental ballistic missiles, it is a significant factor in calculating the trajectory. During its flight, the projectile moves in a straight line,not counting gravitation and air resistance for now). Since the target is co-rotating with the Earth, it is in fact a moving target, relative to the projectile, so in order to hit it the gun must be aimed to the point where the bullet and the target will arrive simultaneously."
Spin Drift--
"Spin Drift" as it is properly used refers to the tendency of a bullet to move in a particular direction,along its flight path) because of the bullet's rotation along its axis. This is actually the function of two things--the gyroscopic effect and the Magnus effect.
Gyroscopic effect: If the bullet has sufficient spin, saying if it rotates fast enough about its axis of form, the gyroscopic effect takes place -- the bullet´s longitudinal axis moves into the direction of the overturning moment, perpendicular to the plane of drag. This axis shift however alters the plane of drag, which then rotates about the velocity vector. This movement is called precession or slow mode oscillation. For right-handed,clockwise) spin bullets, the bullet's axis of symmetry generally points to the right and a little bit upward with respect to the direction of the velocity vector. As an effect of this small inclination, there is a continuous air stream, which tends to deflect the bullet to the right. Thus the occurrence of the yaw of repose is the reason for bullet drift to the right,for right-handed spin) or to the left,for left-handed spin). This means that the bullet is "skidding" sideways at any given moment, and thus experiencing a sideways component.
Gyro Effect:
Magnus Effect,from Wiki)
Spin stabilized projectiles are affected by the Magnus effect, whereby the spin of the bullet creates a force acting either up or down, perpendicular to the sideways vector of the wind. In the simple case of horizontal wind, and a right hand,clockwise) direction of rotation, the Magnus effect induced pressure differences around the bullet cause a downward force to act on the projectile, affecting its point of impact.[8]
The Magnus effect has a significant role in bullet stability because the Magnus force does not act upon the bullet's center of gravity, but the center of pressure affecting the yaw of the bullet. The Magnus effect will act as a destabilizing force on any bullet with a center of pressure located ahead of the center of gravity, while conversely acting as a stabilizing force on any bullet with the center of pressure located behind the center of gravity. The location of the center of pressure depends on the flow field structure, in other words, depending on whether the bullet is in supersonic, transonic or subsonic flight. What this means in practice depends on the shape and other attributes of the bullet, in any case the Magnus force greatly affects stability because it tries to "twist" the bullet along its flight path.[9][10]
Magnus Effect
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Anyway, this thread is now officially locked.
My point in presenting the above info is to show that when this thread got sidetracked on the spin drift matter, some voices were quick to post "You don't know Jack" type statements. And from there it got worse.
In fact we had parties talking about two very different things...
My message is please, folks, refrain from the "you're a fool... you don't know Jack" type remarks.
