The Cavalry Carbine was a shorter weapon than the standard infantry musket of the time, the India Pattern Brown Bess. The Bess had a barrel length of 39 inches, while the carbine was 26 inches.

Carbines were less accurate and less powerful than the longer muskets of the infantry, due to a  lower velocity of a ball fired from the shortened barrel.

So why issue cavalry with a less accurate weapon?

Some people say that it is so that the carbine can be loaded and fired from horseback. However this is unlikely as all light dragoons loaded and fired dismounted. Much more likely is that it is lighter and more importantly easier to carry on horseback. The way British light Dragoons of the time carried their carbines was from a swivel at the bottom of the cartridge belt shown right. A Bess carried that way would keep hitting the horses legs.