I have a vague idea what BC, ogive etc. means but never really studied them.
I do know that the original 30-06 was loaded with 220 grain bullet. Those old parallel sided round nosed fmj bullets would penetrate like crazy.
In modern boat tail, pointed, bullets, a 220 grain bullet would have exceptional range. The trouble with the .308 is the smaller powder space is made even smaller with that weight bullet.
On the other hand, the 6.5x55 plus several other early 6.5s were originally loaded with 160 grain round nose fmj bullets.
Loaded with a 139 grain bullet of high BC or whatever it is, it performs like a very heavy 30 caliber but with less recoil, etc. but it also does not take up case volume.
Same applies to a 6mm with a heavy for caliber low drag bullet.
“...I do know that the original 30-06 was loaded with 220 grain bullet...
...The trouble with the .308 is the smaller powder space is made even smaller with that weight bullet....”
The .30-03 had the 220-gr bullet. The .30-06 first used in the 1903 Springfield used a 150-gr projectile.
Powder space is relative to shank seating depth. You can seat the bullet to any depth you want, you just need a chamber with a long enough of a throat to accommodate the resulting COAL. All it takes is one phone call to Pacific Tool and Gauge and they’ll make you a custom reamer to cut a chamber with whatever throat length you tell them.
All the .264 cartridges they’re talking about were first developed as sporting rounds, and sporting development on them, especially the Creedmore and the Grendel, is ongoing. It’s simply not logical to compare them to a MilSpec cartridge that’s been essentially static for half a century. If you want a relevant comparison, you’ve got to allow the chamber specs to be updated to something more current than 7.62 NATO.
There’s a 1-mile target range about an hour’s drive from my house. I guarantee you no one is finding the target on that range with anything smaller than a .375 (elev. 1200’ msl). A .338 AI won’t get there, much less a .338 Lapua. And they’re loading Ay-Cho-Tee HOT, burning barrels out in less than a thousand rounds.
I know SOCOM isn’t expecting 1-mile sea level shots with whatever rifle they select, but my point is that long range shooting has one thing in common with drag racing: there is no replacement for displacement. The current world-record sniper shot wasn’t made with a .308 or a .264, it was made with a .50 BMG. The simple fact is, when it comes to bullet mass, less is less and more is more, and you can’t do more with less. Sir Isaac wouldn’t allow it. Anybody tells you different is peddling snake oil.