With a direct propane setup, Are all the parts used standard plumbing parts or are they special gas parts?

Thanks all you guys. I'll post up some pics as the project gets underway.

Well I just joined but I've been making spud guns for a few years now. Now on to the question. I'm in the process of planing and building a Carl Gustav rocket launcher spud gun. My question is that if I use a 12" x 3" chamber with propane and the barrel also has a 3" diameter, would this actually fi...