Grenade Launcher, Underbarrel (5e Equipment)
From D&D Wiki
Underbarrel Grenade Launchers are systems which can be attached to a rifle. The range is shorter than that of a dedicated grenade launcher, but it is lighter and you don't need to carry another weapon around. You can use your action to mount an underbarrel grenade launcher onto a firearm. With a mounted underbarrel grenade launcher, you can use an action to fire a grenade at a point up to 200 feet away from you. Once you have fired a grenade from an underbarrel grenade launcher, you must use an action or bonus action to reload it before you can fire it again.
Weight: 2 lb.