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

[Gusmeister]

Much of the brilliance I see in the M1 Carbine is it was made on a 1938 Army request. It's easy from a 21st century perspective to know what do design. It's just Monday morning quarterbacking though. But go back to a post WW1 and pre WW2 design that served well for us and our allies into 1970's. Maybe the design was an engineering dead end and improvement would have been too difficult. But today the rifle/cartridge still do what they were intended to do though certainly outdated.

I hear you guys on the Garand. John Garand had first built it for the 276 but the Army wanted it in 30-06. Despite it's flaws (everything has them) it served very well. Just not very long. Not ideal but it worked very very well. It too was brilliant in its day.