this one. The average distance of a fire fight in WWI (and maybe WWII) was less than 300 meters, which is also the average distance of the trenches in WWI. In many estimates, firefights averaged only 75 meters. That being the case, why were a majority of the battle rifle calibers in the .30 range overpowered (by today's standards) when a more intermediate cartridge would have clearly been sufficient? Obviously most of the militaries in the world changed their minds during the cold war post WWII which is why we have the 5.45 and 5.56, but what was the mentality that equipped soldiers with punishingly powerful .30 caliber'ish options (on all sides) before WW2? I mean...things like the .30-30 existed in the 19th century which clearly dropped a deer or elk. What made all the militaries of the world make those high-powered calibers? Every country at the time was equally culpable. Nobody swayed away from the formula of a .30 caliber pushing 2600+ FPS.