气动操作（gas operating）又称气体作动式（gas action）是一种枪机运作的原理与方式，其原理为利用子弹中的发射药于击发后所产生的高压气体经过枪管上的导孔来推动链接枪机的结构，例如活塞与活塞连杆，或者是导管与增压器，以完成枪机的开锁/闭锁，**与进弹。换言之，子弹产生的高压气就是枪枝与枪机自动/半自动运作的来源；近代自动枪械多数采用气动式系统。另两种半自动枪械运作方式分别是后座作用与反冲作用。

Gas-operation is a system of operation used to provide energy to operate autoloading firearms. In gas operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and chamber a new cartridge. Energy from the gas is harnessed through either a port in the barrel or trap at the muzzle. This high-pressure gas impinges on a surface such as a piston head to provide motion for unlocking of the action, extraction of the spent case, ejection, cocking of the hammer or striker, chambering of a fresh cartridge, and locking of the action. The first gas-operated rifle was designed by Karel Krnka in 1883.