The Salvatore-Dormus has the distinction of being the world’s first semiauto pistol, being patented in 1891. It is chambered for the 8mm Dormus cartridge, and holds 5 rounds in a Mannlicher type clip. Only about 50 of these pistol were made, mostly for an Austrian military trial in 1896/7 (this particular one has an 1897 Austrian military acceptance mark). The gun uses a delayed blowback action, with the shooter’s finger pressure on the trigger acting as the delaying force – not exactly an ideal system!
In Austrian trials (which were the only trials the gun entered) it was rejected in favor of the 1898 Gasser revolver, which would serve until Austria began adopting semiauto handguns in 1907. However, it does hold the distinction of being the earliest automatic pistol to actually be manufactured in more than toolroom prototype numbers (even if its military trials didn’t actually take place until after other guns had come on the market).