Tiny semi-rimless centerfire cartridge developed for the Erika vest-pocket pistol — one of the smallest functioning semi-automatic pistols ever made. More practical than the Kolibri cartridges but still marginal by any defensive standard.
Type: Pistol
Introduced: 1912, Germany
Parent case: None
Standardization: None
Bullet diameter: 0.167" (4.25 mm)
Case length: 0.41" (10.4 mm)
Overall length: 0.56" (14.2 mm)
Max pressure: 25,000 PSI
Rim type: Rimless
Primer: Centerfire
Typical twist rate: 1:12
Muzzle velocity: 750–800 fps
Muzzle energy: 15–17 ft-lbs
Effective range: 15 yd
Common bullet weights: 12 gr
Primary use: Self Defense
Production status: Discontinued
Also known as: 4.25mm Erika · 4.25 Erika
History: Designed by August Menz for the Menz 'Erika' pistol, introduced around 1912 in Suhl, Germany. The pistol was marketed as a ladies' pocket pistol and key-chain companion. Production was limited to pre-WWI manufacture. Complete examples are very rare; the Erika is considered one of the most charming collector miniature pistols in existence.
Notable firearms: Menz Erika Pistol
Similar cartridges: 2.7mm Kolibri, .22 Short