When the gun is apart you'll see a lot of junk and screws here and there (look at picture 8).
We will only be taking one screw out, if your gun is facing right, it's the bottem most right screw you see. It's right next to the barrel assemby and it has a kind of spacer attached to it. Unscrew it and then everything in your gun will be detached except for the barrel turning mechanism. Leave that on. There is a metal rod on the thing you just unscrewed that is "under" the barrel turning mechanism. You have to take it out at an angle to get it loose.
Okay, now we're going to take the barrel assembly off.
Find the screw that attaches the barrel assemby to the airtank section. Unscrew it, take the parts off, remember the right order, and slip your barrel assembly out. While taking this part a small white piece will fall out of the green part (see picture 8, and read the text by it) Don't lose it, and remember where it goes.
The bottem right screw lets you take the airtank+barrel assembly off (still attached by the vynil tubing)
I underlined the part where I tell you to take the barrelassembly off.
Thanks for pointing that out, it's not as clear as it could be, I'll work on that.
About the metal rod, I only remember the one that's attached to the thing with the spring. Do you have the old green/yellow version or the newer blue version ? If you can't figure it out I'll take mine apart to see if I can see it anywhere. (judging from your other post it's a yellow edition.)
About barrels and stuff: I'm not an expert, I just use what I have. Just go with what works for you.