Here you can see the flange on the tube fitting into a groove in the front barrel clamp. This feature locates the guide tube in the front/rear direction. Again, no clips, pins, or other gadgets to break or get lost. When you remove the top half for cleaning the tube drops right out. The space between the guide tube and the gas block measures about 1/2 inch. At first that seems to freak people out a little. The functioning of the rifle is completely unaffected by this space. We have fired thousands of rounds without malfunction. Our tube is modeled on the RPD machine gun which has about a 3/4" space. The reason the original AK guide tube ran all the way to the gas block is simply to use it as a support and save on one extra component.
Here the piston is just coming out of the guide tube.
The piston is now bridging the gap between the guide tube and gas block with a small amount inside each component.
The piston has exited the guide tube and is guided by the gas block.
The piston is fully seated into the gas block.