The smallest gun I would trust my life with is a PPK, and the smallest caliber would be in .32 / 7.65, .380 is fine, just not the smallest I trust to work.
Smith or Franco-German, had bad luck with most of the interarms. ( like 2 out of 3 had issues).
PP and PPk series was a service firearm way before Ian Flemming, so spare me the double ought seven references.