I took a look at the Wikipedia link, and immediately caught the comparison to the Japanese and Italian 6.5mm cartridges.
A brief thought I had was “why wasn’t the Pedersen round revived after WW2 for something like the T48”. If the .276 Pedersen really was similar to the 6.5mm rounds I mentioned above, that might explain a lot—both the Japanese and Italians found their 6.5 cartridges lacking on the battlefield, and began transitioning over to a .30 cartridge.