Which makes sense, as .308 was actually based on the .300 savage scaled up, rather than a 30-06 scaled down as most perceive.
This topic was way off-topic for the thread is was introduced in but warranted discussion.
In 1944, the Army realized that Cartridge, Ball, Caliber .30, M2, when loaded with the current propellant left considerable empty space in the case. And thus started what would later be known as the Lightweight Rifle Cartridge Program, which would later in 1954 yield the 7.62mm NATO cartridge. As a starting point, the Army selected the .300 Savage, but where did the .300 Savage come from?
It turns out that in the late 19-teens, Savage wanted a cartridge that would work in a .30-30 length action but have the performance of the U.S. Service Cartridge, Caliber .30 (.30-06). This they found they could do with then modern propellants. So they shortened a .30-06 case down so that the overall length with a 150 grain bullet was 2.60 inches. The original .300 Savage load was a 150 grain bullet at 2700 fps, which matched Caliber .30, Ball, M1906 performance.
The Army, around 1941 (skipping the M1 Ball story) bumped the velocity of M2 ball up to 2800 fps, which starts to push the capabilities of .300 Savage, so the development of the T65 cartridge (7.62mm NATO) sees the case volume increase as time goes on. That is a story in itself that I will go into later if you want me to, but for now the answer to the question in the title is:
BOTH are correct.