Let's take a look at handguns of WWII:
P08 Luger (aka Parabellum P08), 9x19 mm Para, single action, 8 rounds.
Famous pistol. Few version, 7.65x22 Para version was relised as "commercial" version of P08.
P38 Walther, 9x19 mm Para, double action, 8 rounds.
Outstanding handgun, later Petro Beretta factory a bit changed this gun and maked his Beretta Brigadier then famous Beretta 92. Changes wasn't great - P38 got two springs besides bolt, Beretta - one under barrell...
Walther PP/PPK, 22LR or 6.35mm auto (.25 ACP) or 7.65x17mm Auto (Browning) or 9x17mm (.380 ACP), double action, 7/8 rounds.
Relised as police weapon, these guns widely used in German army and was officially adopted in Navy.
To be continued...