There are some 9mm's that are very comparable in size to the Walther PK-380, i was considering getting one of those myself, they are super sharp looking pistols, but when i held it next to my P7, it was the exact same size. (P7 is a hell of a lot heavier, but it is a 9mm).

I suspect the PK-380 is a really nice shooter though. In a gun of that size the .380 is a total pussycat to shoot. VERY expensive ammo though.