This is an example of the smallest centerfire pistol ever made – a 2.7mm Kolibri semiauto. About a thousand of these were made between 1910 and 1914, firing a 3-grain projectile at about 650 fps (for a total of 3 ftlb of muzzle energy),patented in 1910 and introduced in 1914 by Franz Pfannl, an Austrian watchmaker, with financial support from Georg Grabner.
image/text credit: Forgotten Weapons
It may be insanely impractical, but it’s a great piece of mechanical art – and it comes with 7 rounds of ammo! This pistol failed to sell at auction; it did not meet the (unpublished) reserve price.
The round was not well accepted. The 2mm Kolibri’s small size makes handling and loading individual cartridges difficult, and the bullet itself is fairly weak, with literature at the time suggesting the round was capable of penetrating only 10–40 millimetres (0.39–1.57 in) of pine board.
It had enough muzzle energy to penetrate more than 20 sheets of paper but not a suit jacket (proven by one of my students) and had an effective range of 2 meters, it makes the .25 ACP (at one time carried by many European police agencies) look like a Dirty Harry hand cannon.