Originally Posted by Charlie the sniper
6.5x55 Swedish.......Superb round.
The 6.5 X 55 Swedish/Norwegian is a great round. But it saw only limited service with the Norwegians in World War II.
The U.S. with its 30-60, the Brits with their .303, the Germans with their 7.92mm, and Russians with the 7.62mm all used a bullet in World War II that was a carry over from World War I and was roughly around 30 caliber as their standard infantry caliber. All four calibers were adopted between the late 1880's and 1906. Power wise all four cartridges are fairly close. Any would be effective out to the range at which most soldiers could be accurate.
For the standard soldier I would think the U.S. M-1 rifle which was the only standard issued semi-auto rifle would be best. The Brits, Germans, and Russians all used good bolt action rifles as their standard
The Japanese and Italians used 6.5mm bolt action rifles as their standard infantry weapon. The Japanese started to convert to a 7.7.mm rifle during the war, but many if not most of their soldiers continued to carry 6.5mm weapons.
I would have thought 6.5mm would have been about the perfect caliber for a military rifle. It is powerful enough, and it is easy to designe a high velocity round for a nice flat trajectory. Both the U.S. and the Brits looked at adopting a smaller caliber before World War II, but many factors prevented this.