There's simply no way to get as much sectional density in a factory .270 Win, and essentially no hunting bullets intended for fast twist .277s.
I remember WHEN sectional density was important OR more important than today >>> because of newer Controlled Expansion bullets. S D is a no. indicating the 'supposed' penetrating ability of bullets....
BUT with Controlled Expansion bullets, S D does NOT mean as much as it used to.
There are several examples of 'Light for Caliber' Controlled Expansion bullets pushed at HI velocities. They work too.
Jerry
You can change the bullet technology all you want, but for the same bullet design at two different sectional densities, the higher SD bullet will penetrate better.
There's just no equivalent to say the .264 160gr Weldcore for .277 that will run in a standard twist rifle. Woodleigh makes a .277 180gr Weldcore, and it's a great bullet, but useless in a factory .270Win.
The 6.5CM is a legitimate round to be having a hunting craze. It does something that wasn't readily available until now. Yes, you could get it from custom .277 or .264s on any number of cases, but the key word there was custom.
