Barrel shroud

A barrel shroud is a covering attached to the barrel of a firearm, that partially or completely encircles the barrel which prevents operators from injuring themselves on a hot barrel.Slides, extensions of the that do not fully encircle the barrel, and the receiver (or frame) of a firearm itself are generally not described as barrel shrouds, though they in fact do act as such. Barrel shrouds are commonly featured on air-cooled machine guns, where sustained rapid or automatic fire leave the barrel extremely hot and dangerous to the operator. However, shrouds can also be utilized on semi-automatic firearms, as even a small number of shots can heat up a barrel enough to injure an operator in certain circumstances.

Barrel shrouds are also used on pump-action shotguns. The military trench shotgun features a ventilated metal handguard with a bayonet attachment lug. Ventilated handguards or heat shields (usually without bayonet lugs) are also used on police riot shotguns and shotguns marketed for civilian self-defense. The heat shield also serves as an attachment base for accessories such as sights or sling swivels.

The barrel shroud has been the target of legislative restrictions in the United States, along with other features of certain firearms.

The now-expired Federal Assault Weapons Ban included a barrel shroud in its list of features for which a semi-automatic pistol could be banned (two features in the list were required), the logic being that a barrel shroud would be cool enough for a shooter to grip and better control their firearm. Proposals to restore the assault weapons ban, including this provision, have been made but have been unsuccessful. In the context of that law, the National Rifle Association deemed barrel shrouds a "cosmetic feature".

...
Wikipedia