new to this and a little confused about valves

[mattyg]

I take it that this valve is pull to open except you've put a spring behind the knob to hold it in the open position???
what psi are you running it at??

Ive now made my barrel. I used 2 pieces of hydraulic tube rated at over 600psi sleeved inside each other with blow forward bolt built in
and my QEV arrived in the mail yesterday.
Just gotta get my valve sorted out, some rubber tube for my hop up and I also need to get a mag from a real airsoft gun I want to get one from a Vietnam era m16 AEG as they are straight not like the more modern curved M4 style mag.

Im planning on building it to look like a walther wa2000

So I guess I better start looking for a nice piece of walnut