The .30 carbine is a highly underrated cartridge. I've heard WWII combat vets offering that it was rare to come across a dead GI with an M1 Carbine because the first dogface to find him probably would have swapped his Garand for the carbine.

I've also read accounts beginning about the battle for the Hurtgen Forest/Aachen (which was a strong point in the Siegfried line) and through the end of the Battle of the Bulge, during which time real estate was prone to changing hands a number of times before one side had won out. One side effect of this back-and-forth business was that each side would throw up a makeshift stockade for EPWs, along with some facility for stockpiling the weapons of those prisoners. But the next day might find the other side in control of that piece of ground, and two days later the original occupants might be back. Which gave each side an opportunity to see first-hand which of their weapons their enemy was most fond of.

The American GIs said that whenever they recaptured positions like this, the Germans would have left them all the M1 Garands they could have wished for, but the M1 Carbines would be in short supply. So apparently the Krauts thought it was a fine round, too.

They also said the gun ran great once you figured out the magazines had a lifespan of about two weeks (without mentioning how many reloads a mag might have gone through in that two weeks).

I think I've mentioned in this thread before that the late Jim Cirillo (famous NYPD stake-out squad cop who probably was in more gunfights than any other American LEO of the latter half of the 20th Century) gave the .30 Carbine two thumbs-up. More than once he opined that with a hollowpoint bullet it was even more likely than the .44 Mag or 12-ga with either slugs or 00 buck to produce a one-shot stop. The hitch was he had to have the NYPD armorers work over the M1 Carbine's feed ramp so it would run on hollowpoint bullets.