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

[stanc]

Today the gas port is proven and the gas trap would not even be considered. Back in the 30's, the gas port was not proven or the gas trap wouldn't have even been considered.

Rubbish. In 1940, spitzer bullets had long been proven superior to round-nose bullets for rifle use, yet spitzers were apparently never considered for .30 Carbine ammo.

And you are just flat wrong about the gas port concept being unproven in 1930. I previously noted three gas port weapons (the RSC and Farquhar-Hill rifles, and the Lewis light machine gun) that existed before 1930. Below are four more.

M1909 Benet-Mercie





M1914 Hotchkiss





M1918 Browning





Czech vz26





By 1930, the gas port concept had been well proven. Indeed, it was the gas trap concept that was unproven.