"Funny tho we never hear how under powered a 9mm SMG was..German MP40.. The Carbine has more than double the power of the 9mm.. The Soviets used the 7.62x25 in their SMGs.. 74gr bullet@1600fps.. Killed Germans well enough in the Russian winter.."
The above is very true.
It seems that only the Americans were preoccupied with caliber deficiency issues. The rest of the world seemed satisfied with the caliber of the weapons they used against their foes.