Ugh.
THIS:
Is a SECTOR GEAR.
The SECTOR GEAR is the same on most AEGs. If not the exact same, it works the same.
The SECTOR GEAR determines both the NOZZLE position, and the PISTON position.
They are always THE SAME in relation to each other. As in, the NOZZLE is FORWARD on the PISTON'S forward stroke, and gets drawn BACK on the backstroke.
If the nozzle was BACK on the FORWARD stroke, there would be ZERO seal between the NOZZLE and HOPUP RUBBER. You would get VERY LOW FPS.
The NOZZLE position when the gun is stopped depends on the position of the GEARS. When the gun is NOT being fired, the gears COUNTER ROTATE until they get stopped on the ANTI REVERSAL LATCH. Depending on the position of the BEVEL GEAR's position in relation to the other gears, they might stop with the NOZZLE PART WAY BACK. All that matters is that it is FORWARD when the PISTON is going FORWARD.
So STOP looking into your hopup chamber, the SKY is NOT FALLING.