I agree, anyone with a handle on high school math can see the advantage of the 7mm bullet for military service, although the .30 gave us a better hunting round IMHO. Neither do I understand why the Germans, who already understood the advantages of the 7mm projectile from a battle rifle, chose a .318, then a .32.
Hi
I believe they were worried about armor. They seemed to have convinced themselves that an 8 mm was more effective on troops under cover, or on lightly armored targets.
Bob