Superior for what size game?
I was referring to hunting Moose and Elk here in the west, with the real chance of running into a grizzly.
Sectional density is important for penetration, but if your judging by sectional density alone, then a 243 with a 100 grain bullet is almost equal to your 308 with a 165 grain bullet, (.242 vs .248) so why not just hunt with a 243?
According to that theory, all of the big magnum calibers are unnecessary, and all we really need are 243's.
Sectional density (along with bullet construction and impact velocity) are among the key factors in determining penetration, however
kinetic energy, the ability to do damage, is the most common measure of killing power for rifle bullets.
The 30-06 and even the .358 (for shorter range work) will give you more options as far as bullet weight goes, which makes them both more versatile and thus superior big game rifles.
All of the outfitters in this area won't take you on a grizzly hunt with anything less than a 300 WM.
A 308 might be fine back east, or if you can't handle recoil,
but no serious hunter here in the Rockies hunts with a 308.
Even my wife now uses a 300 WSM.
The 308 is a great cartridge for deer size game , but if you ever come out here, better bring something bigger.
Better off over gunned than under gunned where the game can kill you before you can kill the game.