"Is the .380 cartridge underpowered?"

Been following and contributed to this thread early on...........

What pops into my head every time I see the thread Title is.....LOL

"YES;when compared to a cartridge that starts with a "5" and is fired from a belt fed M-2!!!!!"

IMHO......Eric's post above is as close to a correct answer to the OP's question as you can get!