Carbines
There have been many carbines developed from assault rifles, being essentially shorter rifles firing the same ammunition, although usually at a lower velocity and 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).
The relatively short length and light weight of carbines makes them easier to handle in close-quarter combat situations (such as urban or jungle warfare), or when deploying from vehicles. The disadvantages of carbines, when compared with their longer counterparts, are generally poorer long-range accuracy and shorter effective range.
In BF2 carbines are the primary guns for the spec-ops class. While they do not do as much damage as the assualt rifles, they are very accurate and a good player may be able to snipe with the laser sights.