Andreas Zournatzis himself supplied the answer to this query. What happens is at the end of the shot the piston has reached its most rearwards travel in the gun (remember the piston moves forwards when the "Dreamair" gun is being cocked) with the axle and winding drums assembly still spinning. As they continue to rotate they will start to wrap the inner cable in the opposite direction to which it is usually wound on the inner drum, in which case the piston is dragged forwards again against the air pressure in the gun. This serves to brake the spinning assembly as its rotational inertia cannot do much work against the gun's start pressure, hence a form of "pneumatic braking" takes place on the spinning axle and winding drums assembly.I was just thinking that high speed spinning items can function like a gyroscope which would tend to stabilize the "Dreamair" gun during the shot as the winding drums and axle certainly spin rapidly. Another consideration is that having been spun up to a certain velocity how is their rotational inertia handled in order to bring the spinning assembly to a halt. There does not appear to be a wishbone catcher as such, so that task must fall to the inner cable anchor point which would receive quite a jerk when it pulled up the winding drums and axle assembly to stop them spinning after the shot.