There seems to be the problem of long and short actions.
Long actions are for cartridges 3.34" like a 30-06 or 300 Win mag.
Short actions are for cartridges 2.81" like the .308 and .284.

The surplus '98 Mausers are sort of medium length for cartridges 3.25" like the 8mm. That cartridge needs a long acion, but the 8mm and 257 Roberts both use 7mm type brass, and yet the 257 Roberts is 2.78" and fits in short action.

Most guys will say there is not much difference between a .308 and a 30-06, but that is probably giving the .308 credit for being in a short action. The 8mm is much closer to the 30-06 than a .308, but most people talk about the differences between an 8mm and a 30-06.