Back to the original question: "Can a bullet be overstabilized with too fast a twist?"
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<br>Yes.
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<br>An overly stable bullet travels its full, extreme trajectory in the same slightly tip-high angle of its exit from the slightly muzzle-high angle of the bore. IOW, the farther it goes, the more nearly sideways it meets the air it's passing through. So it slows-down faster than a barely stable bullet with the same launch velocity.
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<br>Ideally stable bullets are just barely stable enough to settle into tip-forward flight without yawing or tumbling. The barely stable bullet travels its full, extreme trajectory (which is longer and "flatter" as a result) tip-forward all the way.
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<br>This is one reason that matching twist length to bullet length is both crucial and (within limits) flexible.
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