Czech Skorpion in .380 ACP - compact and light and only slightly larger and heavier than the weaker .32 ACP version. This short 12-round magazine is compact, but is replaced with 30-round variants when concealment is not required. Note how the magazines on the .380 Skorpions (and 9mm Luger model for that matter) are straight and not curved like the .32s.
Photo and information from:
Black Powder Sports