The gas System is very similar to the blowback system. The only major difference is that the gas system has a piston that is attached to the top of the bolt and it extends far that the bolt in a separate tube. The tube is connected to the barrel. When the bullet is fired the gas from the gun goes up the tube and pushes the piston back. When the piston is back it pushes the bolt back so that a new shot may be loaded. The ejection system works the same as in the Recoil System.