The .22 CB cap (conical breech cap) is a more powerful version of the .22 BB cap (aka: 6mm Flobert) rimfire metallic cartridge, which was invented by Louis-Nicolas Flobert in 1845. The .22 BB cap and .22 CB cap are interchangeable and are relatively quiet, low velocity cartridges, designed for indoor target shooting. History Designed to be a cross between the .22 BB and .22 Short, and first catalogued in around 1888 (though probably first made before that), it "managed to combine about all the disadvantages...[of both] into one generally useless cartridge", being no more accurate than either while being noisier than the .22 BB cap, and penetrating much deeper, requiring a backstop as strong as for the .22 Short, thereby negating the CB cap's advantages for shooting indoors. American ammunition manufacturers dropped the .22 CB cap in the 1940s. In Europe, the .22 BB cap and .22 CB cap are both called "6mm Flobert" and are considered the same cartridge. In Europe, the cartridge is still used in cheap rifles meant for short-range pest control. Although RWS in Germany, Eley-Kynoch in Britain, and Alcan stopped making the 6mm Flobert in the 1970s, it is still manufactured and sold in some European countries. For example, in the Czech Republic and Slovakia, Flobert guns fall within the same weapon category as air rifles, which are usually unaffected by gun laws. 6mm Flobert ammunition is also used in antique firearms chambered for the .22 Short and the .22 Long, as most modern ammunition has much higher pressure than the old black powder cartridges these guns were chambered for. Description The .22 CB cap has a very small propellant charge (usually no gunpowder, just the primer), resulting in a low muzzle velocities of between 350 and 853 feet per second (107 and 260 m/s). Due to their low power, classic CB rounds used in indoor target practice can be trapped by many pellet gun traps since some modern pellet guns exceed the velocity of the CB round (however, this depends on the limits designed in the individual pellet trap). In longer rifle barrels the CB has a very quiet, seemingly non-existent report due to the lack of residual pressure at the muzzle (see Internal ballistics). The CB loses velocity fast in longer barrels, due to the lack of anything other than the primer as a propellant. Modern rounds The original .22 CB cap