Thank you all for your comments they really are appreciated.
Band, the shank is oval which may be causing the flattening you are seeing.
Walle, I wish! I know the name and everything means a lot but the original is worth $3-5,000 I might be lucky and get $100 for this.
SAS,

Looking at the pipe in the flesh I don't see it but in the pics I do, maybe. I had originaly intended to undercut the chamber at the back creating a Cobra type thing but decided I liked the shape as it was.
Sorringowl, use an extra long tennon, face the end of the stem and one side of the extension and glue all three of them together, the other face can be turned square when the glue is set. Or you can try this:

The derlin is roughed with a rasp which makes lots of grooves, the drill bit keeps the airway aligned. The cuts are done on a bandsaw but you should be able to do it with a mitre saw, putting a slight flat on the rod helps a lot.
The pipe is not really a sitter but it rocks nicely, I had a team of top scientists work out the perfect cross axis curve to make it do this.
Sorry but I just had to.
David.