Should the second quote read "The effect of a plastic tip or an empty space in the tip of a bullet is to increase stability relative to a constant density bullet of the same dimensions."?
JBM Ballistics has graciously added an input for the length of the plastic tip to their stability calculator to reflect the "new and improved" formulas presented by Mr. Miller and Mr. Courtney in their January and February 2012 Precision Shooting articles.
And, although it has not yet been...