.22 BB

Frenchman Louis-Nicolas Flobert invented the first rimfire metallic cartridge in 1845.

His cartridge consisted of a percussion cap with a bullet attached to the top.

[4][5] Usually derived in the 6 mm and 9 mm calibres, it is since then called the Flobert cartridge, but it does not contain any powder; the only propellant substance contained in the cartridge is within the percussion cap.

It has no separate propellant charge, relying on the impulse created by the primer alone to fire a round lead ball.

More common is the .22 CB Cap, which fires a slightly heavier conical bullet and is available in a variety of cartridge lengths.

A .22 CB Cap, .22 short, and .22 Long Rifle; the CB Cap is the same length as the BB Cap, but uses a conical bullet.