Checking my Modern Reloading book it lists the 30-30w as being .308 in diameter of the projectile. It also list a round as the .307w which is also of .308 diameter. Apart from the .30 Luger all rounds listed as .30 cal are all listed as being .308 in diameter for the projectile.
The 307 Win has the same outside dimensions as a 308, however, it has a large case rim not unlike a 30/30. The inside case dimensions are different from a 308 as well. The 307 does not have the volume of the 308 and it was actually designed specifically for Win 94 Angle Eject rifles. Subsequently, any factory rounds for a 307 you may come across will be flat/round nose bullets.
Seems to me it came about around the same time as the 7-30 Waters and was developed with the same thoughts in mind...improve upon the 30/30. However, despite a 30/30s appearence as a "limited" bullet by todays ballistics standards, it continues to outlive the now defunct 307 and 7-30.
Now that Hornady has released their new 160gr Leverevolution for the 30/30, it has arrived anew again. I am getting sub inch three shot groups from my short barreled 94 at 100 yards. Fantastic development that allows tube magazine shooters to load spitzer type bullets safely in their slide actions by utilizing a gum-rubber type point that will not ignite a primer, yet, retains its shape for superior bullet flight. Not to mention that these factory loads are very reasonably prices.