One of the earliest metallic cartridges ever made. A round ball seated in a percussion cap with no powder — the primer compound alone drives the projectile. Developed by Flobert in 1845 for indoor parlor shooting galleries.
Type: Rimfire
Introduced: 1845, France
Parent case: None
Standardization: Obsolete / Non-standard
Bullet diameter: 0.222" (5.64 mm)
Case length: 0.28" (7.11 mm)
Overall length: 0.46" (11.68 mm)
Max pressure: 6,000 PSI
Rim type: Rimfire
Primer: Rimfire
Typical twist rate: 1:16
Muzzle velocity: 700–800 fps
Muzzle energy: 20–29 ft-lbs
Effective range: 10 yd
Common bullet weights: 18, 20 gr
Primary use: Target, Pest Control
Production status: Obsolete
Also known as: BB Cap · .22 Bulleted Breech Cap · 6mm Flobert · .22 Flobert
History: The BB Cap is among the first practical self-contained metallic cartridges in history, predating even the .22 Short. Flobert's design placed a round lead ball (BB — 'Bulleted Ball') directly into an enlarged rimfire percussion cap. The priming compound provided all the propellant energy — no powder charge. Muzzle velocity was extremely low, making it suitable only for the quietest indoor ranges.…
Notable firearms: Flobert parlor rifles, Stevens Gallery Rifle, Various 19th-century single-shot rifles
Similar cartridges: .22 CB Cap, .22 Short, 9mm Flobert