Example methods, systems, and apparatus are described herein. An example gas block is described for an automatic firearm, which has a gas cylinder that can be connected in a fluid-tight manner to a hole in the gun barrel via a gas channel, characterized by a control element that can be switched between at least two positions and is designed to open the gas channel in the first position, in which the fluid-tight connection is obtained, and to close the gas channel in the second position, in which the fluid-tight connection is interrupted. The disclosure also relates to a control element, a gun barrel equipped with the gas block, and an automatic firearm equipped with the gas block.