So they are the same case?
I think that MD said that the cases have the same OAL, but that the body of the 8x57 is longer from the bottom of the case to the bottom of the shoulder, and the neck is correspondingly shorter than the 7x57 case
When I compare the 7x57 to 8x57 case dimensions, the overall length of the cases is the same, 57mm, but the length from the bottom of the base to the bottom of the shoulder is 43.84mm for the 7x57 and 46.2mm for the 8x57, a difference of 2.36mm. Since the overall case lengths are the same, 57mm, the difference of 2.36mm is accounted for my different shoulder angles and lengths of the shoulder and neck. The 7x57 has a shoulder length of 3.57mm and a neck length of 9.59mm, while the 8x57's measurements for those portions of the case are 2.7mm and 8.1mm respectively.
Same basic parent case, but after being run through different dies they have different dimensional specs within the shared overall length. IOW, you could make shootable 7x57 cases from 8x57 donor brass or shootable 8x57 cases from 7x57 donor brass.
