Making a bullet longer, holding proportions, for a given weight(like a turned aluminum bullet) will increase BC and result in less windrift.
Picture the shockwave bowed over the bullet nose. It's cross section folding in tight with speed, but unfolding/increasing as velocity drops off(deceleration). A bullet's BC follows this cross section. Effective BC changes in flight(with velocity) as drag goes up. The bullet cross section itself unchanging and insignificant.
Picture wind pushing against the shockwave rather than the bullet sides. And rain never actually touching a bullet in flight.