[teeroux]

Does this mean that .30 Caliber, 30-30, and 30-06 are all .308" rounds fired out of different casings for different purposes?

When 30-30 was developed it still used the black powder system for designation. 30cal bullet on 30gr of powder, but smokless instead of black. 30-06 designation comes from 30cal bullet developed in 1906.

Both utilize a .308in bullet. The 30-30 uses blunt tip bullets,traditionally, and rimmed cases due to tubular magazines. The 30-06 uses a spitzer bullet (pointy tip) and rimless case because it was developed for range, accuracy, and function for bolt action rifles.