The M1 Carbine is the standard by which all PDWs are measured.

[n9nwo]

What the .30 carbine has going for it over the 9mm is being able to do aimed fire out to 100m. Not sure that the 9mm would have the accuracy let alone the energy down range that the .30 carbine would.

Any PDW has to have the ability to engage targets out to 100 m.