The 30-06 is beating the .308 from the get go but from a practical hunting standpoint it is neglegable.

Take Federals 165 grain Nosler solid base bullets and at the muzzle there is only 240 foot pounds difference between the two and then there is only 160 foot pounds difference between the two at 500 yards. That's less than what a what a 17HMR 17 grain bullet produces at the muzzle. Pretty neglegable when hunting big game huh?

Now look at the trajectory. Sight them both to be at zero at 200 yards and there is less than one inch of difference between the two out to 350 yards and only 4.5 inches difference at 500 yards. Again pretty neglegable huh?

Same thing would apply to 180 grain bullets. IMO there is absolutely no reason in the world to use anything heavier than 180 grain bullets in a 30 caliber rifle except for extreme distance target shooting. a 200 grain bullet will not kill anything any faster than a 180 grain bullet will.