A carbine is a firearm similar to a rifle or musket, but generally shorter an of lesser power. Many carbines, especially modern designs, were developed from rifles, being essentially shortened versions of full rifles firing the same ammunition, although usually at a lower velocity. There have also been many where the carbine and rifle adopted by a particular nation were not technically related, such as using completely different ammunition or internal operating systems (though the carbine still being weaker, or of smaller size). Either may be more common, depending on the time period. There are also a limited number of pistol-caliber carbines, designed by integrating the action of a handgun such as a revolver or autoloader into a longer weapon with a rifle barrel and stock. They are generally employed as a more accurate alternative to a traditional handgun, and are used by some police teams and by civilian sport shooters.