I remember asking Ross about that “setscrew” you can see staring down the barrel. He said that particular one is the screw that attached the acrylic tube to the inner most aluminium tube or the sleeve as I call it. When you pushed the metal sleeve inside, the rest of the acrylic tube and the pin moved back as one piece inside the tube and then slowly returned to the same position.
i’m sure he said that you couldn’t see the setscew holding the outer rotating tube in place but it was most likely hidden behind the tube sleeve. He said that the acrylic aluminium sleeve was only an inch or so long and at the very back of it down the bottom was a screw that held in place some kind of white plastic stick of some kind that went back into the depths of the gun body. Possibly having one scew holding the acrylic in place was why so many of the hero guns acrylic seems to have broken off from impact.
So the acrylic tube screws into a 1 inch sleeve ( the smallest of the 3 telescoping tubes) and the sleeve is connected to a piece of plastic running to the internal mech.
The other thing you can see down the end in the middle is the guns strobe