barrel and up to a 10-round capacity, while riot shotguns are often found with barrels of 35 to 46 cm (14 to 18 inches) and a capacity of 5 to 8 rounds. Combat use The combat shotgun has evolved from its original role as a short range combat weapon into a wider role in modern times. With proper configuration, ammunition and training, the modern combat shotgun plays three roles: Offensive weapon Breaching system Less-lethal crowd control Effective range of the shotgun with standard buckshot is limited to about 20–30 meters. Slug rounds, if available, can extend the effective range of the shotgun to 100 meters (although this is also dependent on the shotgun's sighting system; rifle sights and ghost ring sights will allow the average shooter to effectively engage human-sized targets at considerably greater distances than with a bead sight). Less lethal rounds vary, with ranges from 10 meters for rubber buckshot to 75 meters for rubber slugs. These less lethal munitions are the same type as used by police, and have served well in riot control situations, such as that in Kosovo in 2001. When used as a door breaching system, the shotgun may be provided with a muzzle extension to allow it to be pressed firmly against the door while providing the correct standoff distance for optimum performance. While there are specialized rounds for breaching doors with minimal hazard to any occupants of the room, any type of round will do the job, though with some degradation of effectiveness and increased risk of collateral damage. In operations in Iraq, the shotgun was the preferred method of door breaching by infantry units, ideally with a frangible breaching slug. For the breaching role, shorter barrels are preferred, as they are more easily handled in tight quarters. Limited ammunition capacity is one of the primary downsides of the combat shotgun. While box magazines are available in some models (such as shotgun derivatives of the AK-47 design, like the Saiga-12), the tubular magazine is still dominant. This limits capacities; the current US pump shotgun issued, the Mossberg 590, has a 5 or 8 shot capacity depending on barrel length. The tubular magazine does allow easy "topping off" (a tube-fed pump shotgun can be kept shouldered and aimed at a target and ready to fire while being loaded), so training emphasizes the need to load the magazine to full capacity whenever the opportunity