John,
Good work. I have used collet dies for many years set up like you said. They worl very well. Like you said, Lee's instructions really are not the best way to set them up. Also a proper locking ring like the Forster ones are a big help, the Lee ones should be thrown away !!
The set up is one of those things that is very simple to show somebody but hard to actually describe, you did a good job.
Mr Viper, if you blew the alloy cap out the top you used FAR to much force. Used properly the amount of handle pressure on the press is very small. In a cam over press you can darn near do it with just the weight of the handle if you let it fall a short way. The handle with just "click" over centre as the case neck is sized. Jammed collets, blown tops and marked mandrels are class ic examples of an abused and misunderstood collet die. Ignore your own method of setting up and read and understand what John has written.
You don't need to alter the handle pressure to gain more neck tension, once the neck is on the mandrel you can't push it any more. If you want more neck tension just polish the mandrel down a smidge. For a 223 collet die I have three mandrels, one standard and a -1 thou and a -2 thou for greater neck tension.
The collet die is about the best way to size a case neck for a non neck turned/tight necj chamber and may be better than bush dies in a lot of applications. I'd be tempted to try one with my bench rest 6PPC if I could be bothered sizing the neck and body in two operations every loading !!