CB = Conical Ball
You can get CB in a Short case and even Long cases. Originally, they were just primer only, but some manufacturers include some powder. The longer the barrel, the quieter they are, so a pistol vs. rifle is significant.
All versions will fit in a Larger .22 chamber as the round spaces on the rim. However, like .38 in a .357, you will get some buildup in the space where a longer cartridge would sit.
Note that while they all chamber, the action most likely won't feed it correctly unless you have a single shot bolt or a gun designed for shorts and longs.
Traditional CB rounds used a fairly light bullet and flew around 500 ft per second. In many cases, these will have less power than an air gun as mentioned above. However, heaver rounds are now available with a little powder that push 750 feet per second resulting in 30+ ft lbs of energy. These rounds would be more powerful than most air guns, but are also louder. The stronger rounds also might have enough recoil to operate some semi-autos.
You can get these via special order, but are not as easy as air gun pellets.
For reasons of noise, legality, cost, and ammo selection, I prefer air. Also, Massachusetts residents can order all the stuff via the net unlike firearm stuff.
Sent from the bottom of my bowl of Cheerios.