I did some more comparing of various random samples of each bullet, the "new" and "old" Hornady 75gr and the Nosler 77gr.
* The nose length and ogives are very similar on all three bullets.
* The meplat diamter on the "old" 75gr is about 0.02" smaller, and the on the "new" 75gr it is just ever so slightly smaller, than on the 77gr.
* The boattail length on the "old" 75gr is 0.04" longer than on the "new" 75gr and the 77gr which are very close.
* The base diameter on the "old" and "new" 75gr are both about 0.02" smaller than on the 77gr.
* The "old" 75gr is about 0.02" longer than the 77gr. The "new" 75gr is only about 0.005" [very iffy at this precision] longer than the 77gr.
I have a computer program that lets me input various measurements and outputs a bunch of info based on those measurements. At 2750 fps:
* The "old" 75gr has a BC [G1 drag function] of 0.369, an "optimal" twist rate of 1:7.59", and 71.2% "optimal" stability from a 1:9" twist.
* The "new" 75gr has a BC of 0.329, an "optimal" twist rate of 1:7.62", and 71.6% "optimal" stability from a 1:9" twist.
* The 77gr has a BC of 0.334, an "optimal" twist rate of 1:7.89", and 76.9% "optimal" stability from a 1:9" twist.
+ The "optimal" numbers were computed using formulas written by Robert L. McCoy of the US Army's Ballistics Research Lab.
This information is for educational purposes only and is not meant to replace "real world" experience because: a) You won't really know how it'll work in your rifle until you try it, b) even though I tried my best I still suck at measuring things [which is why I shared comparative numbers and not exact measurements], and c) the "real world" is what counts. Please don't sue me.