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

[stanc]

I assumed the 30 carbine round nose bullet was used to improve feed reliability with a short cartridge case and detachable box magazine.

That would seem an unwarranted assumption, since there are cartridges with spitzer bullets and similar case lengths which feed reliably from box magazines.

.351 WSL



7.92 Kurz



.300 BLK

I always thought of the 30 carbine more of pistol caliber ballistics and not rifle ballistics.

Regardless of what you thought, the .30 Carbine is a rifle cartridge that was derived from a rifle cartridge (.32 WSL), for use in a military rifle, not a pistol.