Umarex does a quick explanation of blowback that is in use in airsoft guns, BB guns, and even air guns... "What is blowback when you're talking about an air gun, BB gun, pellet gun, or airsoft pistol whether it be from Umarex Airguns, Pyramyd Air, Airgun Depot, or wherever? This video briefly tells shows what blowback airguns and airsoft guns do whether they use Umarex CO2 cartridges or capsules or Green Gas Fuel like you can get from Elite Force Airsoft."