The load data that I see on websites like Hodgdon has the heavier weight bullets (168gr, 175gr) in .308 winchester going somewhere between 100 and 200 fps faster than the same weights in 7mm-08, so how can that be true? Please explain.
When comparing cartridges of different calibers one can't go off of bullet weight alone. Look at the sectional densities (SD) of the bullet weight for the given caliber. Shooting a 140gr bullet out of a 7mm cartridge is comprable to shooting a 165gr bullet from a .30 caliber cartridge, a 154gr 7mm is comprable to a 180gr .30 cal so on and so forth. The 7-08 is a great cartridge it is just a shame that it is mostly limited to 140gr offerings.