Miller,
it's not the whole truth, the pressure is different!
And I think the shell as well, because the 7x57R has a cone (don't know if it is the right word in english) that means, diameter at the rear is brighter than at the front, so, if you polish the chambers, you nearly won't need an extractor! For the specifications this might be helpful:
http://www.norma.cc/en/Products/Hunting/7x57-R-Mauser/

Gunwolf