I'm sort of around, I pop in from time-to time to see if anything exiting has happened, I've had a few projects going myself in what little free time life has given me, but nothing special, or complete for that matter.
Things really just seem to be very quiet here at the moment,

I have used schraders like that up to pressures far in exceeding what would be safe for PVC, so yes I believe it would be suitable, just make sure you tighten it up tight.

I like the improvised look of the whole thing, good job!

The smaller the better with regard to that! That volume of gas in spudding terminology is referred to as the 'pilot volume' the smaller it is the faster your valve will open, but don't go overboard. My advice would be to copy the size of some existing designs, then it makes it a lot easier to troubl...

Picture isn't loading for me, but I have a reasonable idea of what you're trying to achieve. As a general rule I follow, air chamber as big as you can get it, I know a lot of people will talk about diminishing returns and increased fill time, but that aside, it's not going to be detrimental to perfo...

How big should the chamber be? how long is a piece of string? This question depends on how much power you want from your launcher, try using a brilliant free bit of software called GGDT to estimate your power and performance and have a play around with it, although from what people have gone with be...

Well you'd have to buy an adaptor to convert the threads, but yes they would link together.
The design as you've described it would work too, with a bit of searching round the showcase section you can probably find half a dozen people who have used a similar set-up.
Welcome to the site

I am no ballistics expert, but I somehow have a feeling that having two barrels attached halfway in either combination would probably negate any accuracy gains from the rifling, However if you do choose to do this, I would put the rifled section first, this way the pellet doesn't hit the rifled sect...

Try searching for 'countersunk magnets' they are basically the same but there appears to be quite a large selection of them on ebay fairly cheap with free international shipping. Otherwise, what you could do is simply file a notch into the barrel, doesn't need to go all the way through, but just eno...

If you have quite a strong return spring, or are using heavy ammo, you might find o rings can make quite a bit of difference, but it's worth noting that even if you decide to use o-rings you are going to have to fit the piston and cylinder very closely. With regard to designing o rings, I'll give so...

As a member who started upon this hobby at a very young age, and being here from what could be considered the 'industrial revolution of spudding' throughout it's gradual decline I can speak from experience about the behaviour of the 'modern new member', and can give some observations of how advancem...

If you would like to give it a try you are more than welcome to, although this probably isn't a task for the faint hearted, or one without machine equipment. Seeing as I drew the designs for this a few years ago, not sure if I still have them on my pc, or a programme to open them with, so that might...

Thanks for all the kind comments guys, it is really appreciated. And to answer some questions (from the top): Would recommend trying tung or linseed oil Thanks Gippeto, yeah I've been told by a few people linseed would be a good option, when I next get time to alter it I'll sand the stock down and r...

I was going to wait until I had finished this build properly to release it to the world, but what with the recent talk of death of spudding I decided to come out of hiding and post it anyway. After for the first time getting access to multiple very very expensive machine and cnc tools, for my first ...

Picture hasn't shown, sounds good though, have you got another link? With regards to making the piston, a modified whole medical syringe would work, and would be cheap to replace, but I always found them difficult to work with as they aren't exactly designed with structural rigidity in mind. (eg qui...