CB originally stood for Conical Ball. Used a pointy, cone shaped bullet, and just the primer charge or very little powder to propel it.
Originally meant to be shot in small handguns, that were not really built well enough to handle better. And through other 22's for uses like shooting rats or squirrels up in the attic...
The name has been stuck on low velocity short shells.
If you can find them, get CB Longs. Basically the same performance, on a Long Rifle case, net result, less fouling of the chamber. Not really general plinking ammo, so the cost should not be a big deal. They are long enough to feed somewhat reliably from a magazine, in some rifles. May be worth lookin at.
Cheers
Trev