G&P Hop-up question

[HeReigns]

After taking the barrel nut off a g&p m4 I noticed a small little grub screw on top of the outer barrel. After playing around I figured it was to tighten down and secure the hop-up chamber in place.

I also noticed on the front of the hop-up chamber there is a small spring that pushes the hop-up back into the nozzle when together.

My question is what is the best way to re-assemble this? Do I tighten the grub screw on top of the outer barrel and secure the hop-up? Or do I simply let it sit there and allow the spring to push back on the hop-up?
If option 2 is the best then what is that little screw on top of the outer barrel good for?

Thanks for any help.

[ILLusion]

That screw is actually there to make sure the outer barrel remains properly oriented against the upper receiver. The grub screw should stick out of the outer barrel and should fit in to a slot of the upper receiver's barrel entrance. It keeps the outer barrel from twisting when installing the barrel nut. Otherwise, if the outer barrel twists, then the inner barrel will twist as well and the hop up effect will cause your BBs to hook left or right.