This would allow the piston to move back easily?
Wouldn't this setup be different than the one I proposed?

I think I have my model selected. I am going for a very simple one because I am a complete beginner. I have:
-QEV
-Slide Valve
-12oz Co2 paintball tak
-Ball valve
-Connectors for each part


What I plan to do:

-Place a spring in my QEV to help it reset

-Have my air tank on the « A » port of my QEV ...

Thank you Jrrdw, so all I need is the tank, adapters so everything fits, my qev, barrel and slide valve? Do I need anything else between those parts? or simply the release of the slide valve will be okay?

Well I found different models and sometimes they greatly vary. Ive seen that the release from the slide valve allows for a change of pressure, pushing the piston and letting the air out.
So if I have my QEV, my co2 tank on the bottom entry hole, my barrel on the R hole and the slide valve on the ...

I basically never posted, but I am currently building a QEV/Slide valve gun and I am sort of lost. I've looked up many models and I believe I understand the QEV but I would like to know what parts I would need to make the basic gun.

I have:
QEV (QE-04)
Slide Valve (1/2")

What parts do I need ...