To assume old factory loadings is biased against the 7x57. A lot of factory ammo was risk adverse under loaded because of ancient rolling block military 7x57s ... At least per an article I read decades ago. A reason the 7x57 was regarded as a lacklustre cartridge. Underloaded factory ammunition inlaw suit happy USA. Also the USA with the insistence of factory ammunition. Most other places hand loading is far more the norm. And the larger powder capacity shoukd easily outdo the 7mm08 with reasonable handloads. Sure not by much but ...

The .275 HV ammo for the 7x57 I would guess were NOT limited by under loading? Designed for specific Mauser 98 rifles. Still were around a long enough time ago it should be possible to exceed today.