I don't really know how to formulate this question. I guess the best question I can come up with is what does sectional density have to do with external ballistics? What does it have to do with penetration and energy transfer?

For instance. I shoot a 6.5mm 140gr. bullet out of a 260. I would have to refer to my notes as to what the velocities are. This bullet is being listed as a sectional density of .287. A 220gr 338 bullet is listed as .281 and a 30 cal 180gr. is listed as .271.

I know that bullet design has a lot to do with expansion, energy transfer, etc... But this year I was astonished at the damage my 260 did to the deer it shot. And compared that with damage I have seen done to deer with other calibers such as 25-06, 30-06, 270 300 Win Mag, etc...I was wondering how much of that had to do with sectional density.