I suspect you've misinterpreted "Drift" in the table. This is not gyroscopic drift (a still-air constant) but wind drift, the effect of the fact that the bullet is moving through a fluid (air) which may itself be in motion relative to the stationary rifle and target.

The posted tables are calculated to show the displacement of POI from still-air zero (already adjusted for gyroscopic drift) as the result of a 10mph 90-degree crosswind - an arbitrary but useful fiction from which one can extrapolate the actual "windage" required in a wind of different speed and angle. Such information is critical in long-range competition where a gentle breeze can move one's otherwise-perfect shot over to an adjacent target at 1000 yards.

Image below is Hatcher's concise explanation of gyroscopic drift. For a more thorough discussion, see   (You need to Login) and/or   (You need to Login

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